Physics Practice Questions
Exam Duration: 120 Mins Total Questions : 100
Joule-secondis the SI unit of
- (a)
Eistein's constant
- (b)
Boltzmann's constant
- (c)
Planck's constant
- (d)
Loschmidt's constant
A ball is rolled off along the edge of table (horizontal) with velocity 4 ms-1.It hits the ground after time 0.4 s.Which one of the following is wrong
A: The height of the table is 0.8 m
B: It hits the ground at angle of 60° with the vertical
C: It covers a horizontal distance 1.6 m
D: It hits the ground with vertical velocity 4 ms-1
- (a)
If A and C are correct
- (b)
If B and D are correct
- (c)
If A and B are correct
- (d)
If C and D are correct
A 600 kg rocket is set for a vertical firing. If the exhaust speed is 1 km \(s^{-1}\), the mass of the gas ejected per secound to supply the thrust needed to overcome the weight of rocket is
- (a)
117.6 kg \(s^{-1}\)
- (b)
58.6 kg \(s^{-1}\)
- (c)
6 kg \(s^{-1}\)
- (d)
76.4 kg \(s^{-1}\)
A rod elongates by t when a body of mass M is suspend from it. The work done is
- (a)
Mgl
- (b)
\(1\over2\)Mgl
- (c)
2 Mgl
- (d)
zero
If the kinetic energy of a moving body (velocity \(\vartheta \))is directly proportional to time t, the magnitude (F) of the force acting on the body is proportional to
- (a)
\(\sqrt { t } \)
- (b)
(t)-1/2
- (c)
\(\vartheta \)
- (d)
(\(\vartheta \))-1
if the distance between the sun and the earth is increased to four times its present value. the centripental force of the revolution of the will
- (a)
increase to four times its present value
- (b)
decrease to sixteen times its present value
- (c)
increase to sixteen times its present value
- (d)
increase to eight times its presnt value
two identical objects of mass M are initially separated by a very distance. if each object is released from rest and allowed to gravitate toward the other when the sepration of the particles is R, their relative velocity is
- (a)
\(\sqrt { \frac { GM }{ R } } \)
- (b)
\(\sqrt { \frac { 2GM }{ R } } \)
- (c)
\(\sqrt [ 2 ]{ \frac { GM }{ R } } \)
- (d)
\(\frac { 1 }{ 2 } \sqrt { \frac { GM }{ R } } \)
how much energy will be necessary for making a body of 500 kg escape from the earth?
(g= 9..8 ms-2 radius of the earth = 6.4x106 m)
- (a)
about 9.8 x 106 j
- (b)
about 6.4 x108 j
- (c)
about 3.1 x1010 j
- (d)
about 27.4 x1012 j
A truck carries a water tank and moves with an acceleration of 3 ms-2.The slope of water surface shall be
- (a)
0.153
- (b)
0.612
- (c)
0.306
- (d)
1.00
If we dip capillary tubes of different radii in water and water rises to different heights h in them,then
- (a)
\(\frac{h}{r^2}\) = constant
- (b)
\(\frac{h}{r}\) = constant
- (c)
hr = constant
- (d)
\(hr^2\) = constant
If for a gas \(\frac{R}{C_\vartheta}\)= 0.67 the gas is made up of
- (a)
diatomic molecules
- (b)
mixture of diatomic and polyatomic molecules
- (c)
monoatomic molecules
- (d)
polyatomic molecules
Air is filled at 60°C in a vessel of open mouth.The vessel is heated to a temperature T so that one-fourth part of air escapes.Assuming the volume of the vessel remaining constant, the value of T is
- (a)
80°C
- (b)
143°C
- (c)
333°C
- (d)
416°C
A spring with zero relaxed length and spring constant k = 50 \({ Nm }^{ -1 }\) moves a block by contracting from a stretched length of 25 cm to a length of 5 cm. The block of mass m = 0.5 kg slides on a horizontal frictionless surface. The amount of work done on the block by the spring is
- (a)
2.188 J
- (b)
0.50 J
- (c)
1.500 J
- (d)
15 kJ
A system exhibiting S.H.M. must possess
- (a)
elasticity as well as inertia
- (b)
elasticity,inertia and an external force
- (c)
elasticity only
- (d)
inertia only
The relation between phase difference and path difference is
- (a)
\(\triangle \phi \quad =\quad \frac { 2\pi }{ \lambda } (\triangle x)\)
- (b)
\(\triangle \phi \quad =\quad 2\pi \lambda (\triangle x)\)
- (c)
\(\triangle \phi \quad =\quad \frac { 2\pi \lambda }{ \triangle x } \)
- (d)
\(\triangle \phi \quad =\quad \frac { 2\triangle x }{ \lambda } \)
Choose INCORRECT statement :
- (a)
Gas thermometers are used as standard temperatures with very wide temperature range
- (b)
Electric thermometers are more accurate than any gas thermometers
- (c)
Thermo-electric thermometers are used to measure varying temperatures between -250\(?\) and 1500\(?\) because the junction has a low heat capacity.
- (d)
Resistance thermometers are used to measure liquid temperatures accurately between -200\(?\) and 1200\(?\).
The ratio of thermal conductivities of two rods is 5 :2. If the thermal resistance of the two rods of same thickness of these materials is same, then the ratio of lengths of the rods is
- (a)
5/2
- (b)
2/5
- (c)
1
- (d)
5/7
If a current is passed in thermocouple formed of two dissimilar metals, one junction is heated and other is cooled. If \({ \pi }_{ 1 }\) and \({ \pi }_{2 }\) are the Peltier coefficients of cold and hot junctions, then the net e.m.f. across the junction is
- (a)
\(1/2{ { {( { \pi }_{ 1} }^{ }+\pi }_{ 2 } }^{ })\)
- (b)
\({ { { { \pi }_{ 2 } }^{ }-\pi }_{ 1 } }^{ }\)
- (c)
\({ { { { \pi }_{ 2 } }^{ 2 }-\pi }_{ 1 } }^{ 2 }\)
- (d)
\(\sqrt { { \pi }_{ 1 }{ \pi }_{ 2 } } \)
The resistance of a cell does not depend upon
- (a)
current drawn from the cell
- (b)
temperature of the electrolyte
- (c)
concentration of electrolyte
- (d)
e.m.f. of the cell
In a dip circle the plane of oscillation of the needle is adjusted in such a way that it lies
- (a)
perpendicular to the magnetic meridian
- (b)
in the magnetic meridian
- (c)
45° to the magnetic meridian
- (d)
parallel to the magnetic moment
Susceptibility is positive and large for a
- (a)
paramagnetic substance
- (b)
ferromagnetic substance
- (c)
diamagnetic substance
- (d)
non-magnetic substance
Two lamps of liminous intensity of 8 Cd and 32 Cd respectively are lying at a distance of 1.2 m from each other. Where should a screen be placed between two lamps such that its two faces are equally illuminated due to two sources?
- (a)
10 cm from 8 Cd lamp
- (b)
10 cm from the 32 Cd lamp
- (c)
40 cm from 8 Cd lamp
- (d)
40 cm from 32 Cd lamp
Electromagnetic waves are
- (a)
affected by electric field
- (b)
affected by magnetic field
- (c)
not affected by electric and magnetic field
- (d)
both (a) and (b).
The work function of a photoelectric material is 3.3eV. Its threshold frequency will be
- (a)
\(8\times10^{14}Hz\)
- (b)
\(5\times10^{33}Hz\)
- (c)
\(8\times10^{10}Hz\)
- (d)
\(4\times10^{11}Hz\)
The size of atom is nearly equal to
- (a)
1 nm
- (b)
1 micron
- (c)
\(1\dot { A } \)
- (d)
1 fermi
The pure semiconductor has
- (a)
an infinite resistance at \({ 0 }^{ \circ }\)C
- (b)
a finite resistance which does not change with temperature
- (c)
a finite resistance which decreases with temperature
- (d)
a finite resistance which increases with temperature
In common-emitter circuit, the voltage gain is
- (a)
lowest
- (b)
highest
- (c)
zero
- (d)
Same as in common-base circuit
The numerical aperture of an optical fibre depends on
A. core refractive index
B. cladding refractive index
C. critical angle
Mark :
- (a)
if A, B are correct only
- (b)
if B, C are correct only
- (c)
if A, C are correct only
- (d)
if A, B, C all are correct
When a charged particle moves in a crossed electro-magnetic field with a velocity \(\vartheta \) without deviation, then
- (a)
\(\vartheta \) is constant and it is proportional to field
- (b)
\(\vartheta \) is constant and it is inversely proportional to field
- (c)
\(\vartheta \) is equal to ratio of electric field to magnetic field
- (d)
\(\vartheta \) is equal to ratio of magnetic field to electric field
Water is flowing continuously from a tap having an internal diameter of 8\(\times\) 10-3 m. The water velocity as it leaves the tap is 0.4 ms-1 . The diameter of the water stream at a distance 2X10-1 m below the tap is close to
- (a)
7.5X10-3 m
- (b)
9.6X10-3 m
- (c)
3.6X10-3 m
- (d)
5.0X10-3 m
The respective number of significant figures for the number 23.023, 0.0003 and \(21 \times 10^{-3}\) are
- (a)
5, 1, 2
- (b)
5, 1, 5
- (c)
5, 5, 2
- (d)
4, 4, 2
The change in the value of g at a height h above the surface of the earth is the same as at a depth d below the surface of the earth. When both d and h are much smaller than the radius of the earth, then which one of the following is correct?
- (a)
\(d={h\over 2}\)
- (b)
\(d={3h\over 2}\)
- (c)
d=2h
- (d)
d=h
A particle of mass m is at rest at the origin at time t = 0. It is subjected to a force F(t) = F0e-bt in the X - direction. Its speed v(t) is depicted by which of the following curves ?
- (a)
- (b)
- (c)
- (d)
A rod of ferromagnetic material with dimensions 10 cm X 0.5 cm X 0.2 cm is placed in a magnetic field of strength 0.5 X 104 A/m as a result of which a magnetic moment of 5 A-m2 is produced in the rod. The value of magnetic induction will be
- (a)
0.54 T
- (b)
0.358 T
- (c)
2.591 T
- (d)
6.28 T
A vessel of volume V contains a mixture of 1 mole of hydrogen and 1 mole of oxygen(both considered as ideal).Let f1(V) dv, denotes the fraction of molecules with speed between v and (v+dv) with f2 (v)dv, similarly for oxygen, then
- (a)
f1(v)+f2(v)=f(v) obeys the Maxwell's distribution law
- (b)
f1(v),f2(v) will obey the Maxwell's distribution law
- (c)
Neither f1(v) nor f2(v) will obey the Maxwell's distribution law
- (d)
f2(v) and f1(v) will be the same
A container with insulating walls is divided into two equal parts by a partition fitted with a valve. One part is filled with an ideal gas at a pressure p and temperature T, whereas the other part is completely evacuated. If the valve is suddenly opened, the pressure and temperature of the gas will be
- (a)
p/2, T
- (b)
p/2, T/2
- (c)
p,T
- (d)
p, T/2
Find the amplitude of vibration of the particles through which a sound wave of intensity 2x10-6Wm-2 and frequency is 1 kHz is passing.Density of air=1.2kgm-3 and speed of sound in air =330m/s.
- (a)
1.8x10-4m
- (b)
1.6x10-8m
- (c)
2.4x10-8m
- (d)
1.6x10-2m
A damped oscillator of frequency v1 is driven by an external periodic force of frequency v2. when steady state is reached, frequency of oscillator will be
- (a)
\(v_{2}\)
- (b)
\(v_{1}\)
- (c)
\(\frac{v_1+v_2}{2}\)
- (d)
\(\sqrt{v_1+v_2}\)
A photon of energy E is incident on a photosensitive substance of work function \(\phi \) such that \(E<\phi \). Consider the two statements
I. Photoelectric effect necessarily takes place
II. The excess energy (in the form of KE) of the emitted electron is exactly \(E-\phi \)
- (a)
Both (I) and (II) are correct
- (b)
(I) is correct but not (II)
- (c)
(II) is correct but not (I)
- (d)
Both (I) and (II) are incorrect.
Electron in a hydrogen atom is replaced by an identically charged particle with mass 207 times that of electron. Now, the radius of K shell will be
- (a)
2.56X10-3Ao
- (b)
109.7X10-3Ao
- (c)
1.21X10-3Ao
- (d)
22174.4Ao
Ozone layer above the earth's atmosphere will not
- (a)
prevent infrared radiations from sun reaching on the earth
- (b)
prevent infrared radiations originated from the earth from escaping the earth's atmosphere
- (c)
prevent ultraviolet rays from sun
- (d)
reflect back radio waves
Modulation is done in
- (a)
transmitter
- (b)
radio receiver
- (c)
communication channel
- (d)
None of the above
When p-n junction diode is forward biased, then
- (a)
the depletion region is reduced and barrier height is increased
- (b)
the depletion region is widened and barrier height is reduced
- (c)
both the depletion region and barrier height are reduced
- (d)
both the depletion region and barrier height are increased
Energy required for the electron excitation in Li2+ from the first to the third Bohr orbit is
- (a)
36.3 eV
- (b)
108.8 eV
- (c)
122.4 eV
- (d)
12.1 eV
Two lenses of power - 15D and + 5D are in contact with each other. The focal length of the combination is
- (a)
- 20 cm
- (b)
- 10 cm
- (c)
+ 20 cm
- (d)
+ 10 cm
Light propagates 2 cm distance in glass of refractive index 1.5 in time t0. In the same time, t0 light propagates a distance of 2.25 cm in medium. The refractive index of the medium is
- (a)
4/3
- (b)
3/2
- (c)
8/3
- (d)
None of the above
Which of the following is a derived unit?
- (a)
Unit of mass
- (b)
Unit of length
- (c)
Unit of time
- (d)
Unit of volume
A mass of 50 kg is raised through a certain height by a machine whose efficiency is 90%; the energy spent is 5000 1. If the mass is now released, its KE on hitting the ground shall be:
- (a)
5000 J
- (b)
4500 J
- (c)
4000 J
- (d)
5500 J
A dish of mass 109 is kept floating horizontally in the air by firing bullets each of mass 5 g with the same velocity. If 10 bullets are fired per second and the bullets rebound with the same velocity, then the velocity of each bullet is:
- (a)
196 cm/sec
- (b)
98 cm/sec
- (c)
49 cm/sec
- (d)
none of these
The moment of inertia of a body does not depend on:
- (a)
the mass of the body
- (b)
the angular velocity of the body
- (c)
the axis of rotation of the body
- (d)
the distribution of the mass in the body
A phonograph turn-table rotating at 78 rev/min slows down and stops in 30 see after the motor is turned off. Then the revolutions in rev/min made by it in this time are:
- (a)
19.5
- (b)
39
- (c)
78
- (d)
156
A car starts from rest and moves with constant acceleration. The ratio of the distance covered in the n th second to that covered in n seconds is:
- (a)
\(\frac { 2 }{ { n }^{ 2 } } -\frac { 1 }{ n } \)
- (b)
\(\frac { 2 }{ { n }^{ 2 } }+\frac { 1 }{ n } \)
- (c)
\(\frac { 2 }{ n } -\frac { 1 }{ { n }^{ 2 } } \)
- (d)
\(\frac { 2 }{ n } +\frac { 1 }{ { n }^{ 2 } } \)
The Fahrenheit and Kelvin scales of temperature will give the same reading at
- (a)
-40
- (b)
313
- (c)
574.25
- (d)
732.75
A thermometric liquid which can be used to measure temperature between - 40°C to 40°C is:
- (a)
water
- (b)
alcohol
- (c)
mercury
- (d)
phenol
Two vessels of different materials are similar in size in every respect. The same quantity of ice filled in them gets melted in 20 minutes and 40 minutes respectively. The ratio of thermal conductivities of the metals is:
- (a)
5 : 6
- (b)
6 : 5
- (c)
3 : 1
- (d)
2 : 1
A polished metal plate has a rough and black spot. It is heated to 1400 K and brought immediately in a dark room. Which of the following is true?
- (a)
The spot will appear brighter than the plate
- (b)
The spot will appear darker than the plate
- (c)
The spot and plate will appear equally bright
- (d)
None of the above
The ceiling of a hall is 40 m high. For maximum horizontal distance, the angle at which the ball may be thrown with a speed of 56 ms-1 without hitting, the ceiling of the hall is
- (a)
25°
- (b)
30°
- (c)
45°
- (d)
60°
A projectile is projected with a linear momentum p making angle8with the horizontal. The change in momentum of the projectile on return to the ground state will be:
- (a)
2p
- (b)
2pcosθ
- (c)
2psinθ
- (d)
2ptanθ
Two balls of same mass are projected with the same speed one vertically upwards and the other at angle 60° with the vertical. The ratio of their potential energy at the highest point is:
- (a)
3:2
- (b)
2:1
- (c)
4:1
- (d)
4:3
A projectile has initially the same horizontal velocity as it would acquire if it had moved from rest with uniform acceleration of 3 ms-2 for 0.5 minutes. If the maximum height reached by it is 80 m, then the angle of projection is:
- (a)
tan-13
- (b)
\(tan^{-1}\left(3\over 2\right)\)
- (c)
\(tan^{-1}\left(4\over 9\right)\)
- (d)
\(sin^{-1}\left(4\over 9\right)\)
A body revolving in a circle with uniform speed possesses:
- (a)
normal acceleration
- (b)
uniform acceleration
- (c)
tangential acceleration
- (d)
none of these
A vehicle of mass 1500 kg is moving along a curved path of length 314 m with a speed of 20 ms -1. If it takes a turn of 90°, the centripetal force needed by the vehicle is:
- (a)
1000 N
- (b)
2000 N
- (c)
3000 N
- (d)
4000 N
Which of the following statements is false for a particle moving in a circle with a constant angular speed?
- (a)
The velocity vector is tangent to the circle
- (b)
The acceleration vector is tangent to the circle
- (c)
The acceleration vector points to the centre of the circle
- (d)
The velocity and acceleration vectors are perpendicular to each other
A spirit level is placed at the edge of a turn-table along its radius. The bubble will lie:
- (a)
at the centre
- (b)
at the outer edge
- (c)
at the inner edge
- (d)
will oscillate about the centre
At any instant a projectile is moving with velocity u in a direction making an angle α with horizon. After what time the direction of motion turns through an angle θ?
- (a)
\(u\ cos\theta\over g\ sin\ (\theta-\alpha)\)
- (b)
\(u\ sin\theta\over g\ cos\ (\theta-\alpha)\)
- (c)
\(u\over g\ sin\ (\theta-\alpha)\)
- (d)
\(u\over g\ cos\ (\theta-\alpha)\)
A particle crossing the origin of co-ordinates at time t = 0, moves in the XY-plane with a constant acceleration a in the Y-direction. If its equation of motion is y = bx2 (b is a constant), its velocity component in the X-direction is
- (a)
\(\sqrt{2b\over a}\)
- (b)
\(\sqrt{a\over 2b}\)
- (c)
\(\sqrt{a\over b}\)
- (d)
\(\sqrt{b\over a}\)
The ratio of the radii of planets A and B is K1 and ratio of acceleration due to gravity on them is K2. The ratio of escape velocities from them will be:
- (a)
K1K2
- (b)
\(\sqrt { { K }_{ 1 }{ K }_{ 2 } } \)
- (c)
\(\sqrt { \frac { { K }_{ 1 } }{ { K }_{ 2 } } } \)
- (d)
\(\sqrt { \frac { { K }_{ 2 } }{ { K }_{ 1 } } } \)
Two particles P1 and P2 are moving with velocities V1 and V2 respectively. Which of the following statements about their relative velocity vr12 is true?
- (a)
vr12 cannot be greater than v1 + v2
- (b)
vr12 cannot be greater than v1 - v2
- (c)
vr12 > (v1 + v2)
- (d)
vr12 < (v1 + v2)
The change in potential energy when a body of mass m is raised to a height nR from the earth's surface is: (R = radius of the earth)
- (a)
mgR\([\frac{n}{(n-1)}]\)
- (b)
mgR
- (c)
mgR\([\frac{n}{(n+1)}]\)
- (d)
mgR\(\left[ \frac { { n }^{ 2 } }{ ({ n }^{ 2 }+1) } \right] \)
A particle moves along a straight line Ox. At a time t (in seconds) the distance x (in metres) of the particle from O is given by:
x = 40 + 12t-t3
How long would the particle travel before coming to rest?
- (a)
16 m
- (b)
24 m
- (c)
40 m
- (d)
56 m
An engineer claims to have made an engine delivering 10kW power with fuel consumption of I g/s. The calorific value of fuel is 2 kcal/g. This claim is:
- (a)
valid
- (b)
invalid
- (c)
depends on engine design
- (d)
dependent on load
The rate of mass of the gas emitted from rear of a rocket is initially 0.1 kg/sec. If the speed of the gas relative to the rocket is 50 m/sec and mass of the rocket is 2 kg, then the acceleration of the rocket (in m/sec2) is:
- (a)
5
- (b)
5.2
- (c)
2.5
- (d)
25
A particle moves along x-axis and its displacement at any time is given by x( t) = 2t3 - 3t2 + 4t in Sl units. The velocity of the particle when its acceleration is zero, is :
- (a)
2.5 ms-1
- (b)
3.5ms-1
- (c)
4.5ms-1
- (d)
8.5ms-1
A car moves from A to B with a speed of 30 kmph and from B to A with a speed of 20 kmph. What is the average speed of the car?
- (a)
50 kmph
- (b)
25 kmph
- (c)
10 kmph
- (d)
24 kmph
In isothermal process, which of the following is not true?
- (a)
Temperature remains constant
- (b)
Internal energy does not change
- (c)
No heat enters or leaves the system
- (d)
one of the above
A string is wrapped around a cylinder of mass M and radius R. The string is pulled vertically upwards to prevent the centre of mass from falling as the cylinder unwinds the string. The tension in the string is:
- (a)
Mg/6
- (b)
Mg/3
- (c)
Mg/2
- (d)
2Mg/3
A shell at rest at the origin explodes into three fragments of masses 1 kg, 2 kg and m kg. The 1 kg and 2 kg pieces fly-off with speeds of 5 ms-1 along x-axis and 6 ms-1 along y-axis respectively. If the m kg piece flies-off with a speed of 6.5 ms-1, the total mass of the shell must be:
- (a)
4 kg
- (b)
5 kg
- (c)
3.5 kg
- (d)
4.5 kg
A body of mass 3 kg acted upon by a constant force is displaced by S meter, given by relation S = \(\frac { 1 }{ 3 } \)t2, where t is in second. Work done by the force in 2 seconds is:
- (a)
\(\frac { 8 }{ 3 } \)J
- (b)
\(\frac { 19 }{ 5 } \)J
- (c)
\(\frac { 5 }{ 19 } \)J
- (d)
\(\frac { 3 }{ 8 } \)J
A bubble of 8 mole of helium is submerged at a certain depth in water. The temperature of water increases by 30°C. How much heat is added approximately to helium during expansion?
- (a)
4000 J
- (b)
3000 J
- (c)
3500 J
- (d)
4500 J
- (e)
5000 J
An ice cube is kept on an inclined plane of angle 30°. Coefficient of kinetic friction between the block and the inclined plane is (1/\(\sqrt{3}\)). What is the acceleration of block?
- (a)
Zero
- (b)
2 m/s2
- (c)
1.5 m/s2
- (d)
5 m/s2
The mass of the body is 10.000 g and its volume is 10.00 cm3. If the measured values are expressed upto the correct significant figures, the maximum error in the measurement of density is:
- (a)
0.0011 g cm-3
- (b)
0.001 g cm-3
- (c)
0.0001 g cm-3
- (d)
0.021 g cm-3
A rigid spherical body is spinning around an axis without any external torque. Due to temperature its volume increases by 3%. Then percentage change in its angular speed is:
- (a)
-2%
- (b)
-1%
- (c)
-3%
- (d)
1%
The ratio of the radii of gyration of a circular disc about a tangential axis in the plane of the disc and of a circular ring of the same radius about a tangential axis in the plane of the ring is:
- (a)
2:3
- (b)
2:1
- (c)
\(\sqrt{5}: \sqrt{6}\)
- (d)
\(1:\sqrt{2}\)
A ball of mass 109 moving perpendicular to the plane of the wall strikes it and rebounds in the same line with the same velocity. If the impulse experienced by the wall is 0.54 N s, the velocity of the ball is:
- (a)
27 ms-1
- (b)
3.7 ms-1
- (c)
54 ms-1
- (d)
37 ms-1
- (e)
5.4 ms-1
A physical quantity y = has four observables a, b, c and d. The percentage error in a, b, c and dare 2%, 3%,4% and 5% respectively. The error in ywill be:
- (a)
6%
- (b)
11%
- (c)
12%
- (d)
22%
Given \(\vec { C } =\vec { A } \times \vec { B } \)and\(\vec { D} =\vec {B } \times \vec { A } \) . What is the angle between \(\vec { C } \) and \(\vec { D } \)?
- (a)
30o
- (b)
60o
- (c)
90o
- (d)
180o