

NTSE SAT Physics - Current Electricity
Exam Duration: 45 Mins Total Questions : 30
The resistance of a metallic wire becomes 8 times when
- (a)
length is doubled
- (b)
length is tripled
- (c)
length is doubled and radius is halved
- (d)
length is halved and radius is doubled
An electric bulb draws 1.2 A current at 6 V. The resistance of the filament of the bulb
- (a)
2.5Ω
- (b)
5Ω
- (c)
7.2Ω
- (d)
20Ω
A resistance with a resistance Ris connected to a battery with a voltage V to produce a current I. What would be the new current (in terms of I) if the voltage is doubled
and resistance is halved?
- (a)
4I
- (b)
I/4
- (c)
2I
- (d)
I/2
An electric appliance with a current of I and a resistance of R converts energy to other forms at a rate of P when connected to a 120 V outlet. What would be the new
power rating (in terms of P) if resistance is doubled (same 120 V outlet is used)?
- (a)
P
- (b)
2P
- (c)
P/2
- (d)
4P
The resultant resistance of the circuit is
- (a)
0.33Ω
- (b)
16Ω
- (c)
3Ω
- (d)
2Ω
The resistance of an electric bulb drawing 1.2A current at 6.0 V is _____
- (a)
0.5W
- (b)
5W
- (c)
0.2W
- (d)
2W
In the figure,
- (a)
6W, 3 Wand 9 Ware in series
- (b)
9Wand 6 Ware in parallel and the combination is in series with 3 W
- (c)
3W, 6 Wand Ware in parallel
- (d)
3 W, 6 Ware in parallel and 9 Wis in series
Kilowatt-hour is the unit of _______
- (a)
Potential difference
- (b)
Electric power
- (c)
Electrical energy
- (d)
Charge
When there is an electric current passing through a wire, the particles moving are ______
- (a)
Electrons
- (b)
Protons
- (c)
Atoms
- (d)
Ions
A battery is used to _____
- (a)
Maintain a potential difference
- (b)
Measure electric current
- (c)
Measure electric potential
- (d)
Safeguard against short-circuit
The unit of electrical potential is ________
- (a)
ampere
- (b)
coulomb
- (c)
volt
- (d)
watt
______ invented a simple electrochemical cell
- (a)
Archimedes
- (b)
Edison
- (c)
Volta
- (d)
Coulomb
The unit of resistance is ______
- (a)
coulomb
- (b)
volt
- (c)
ohm
- (d)
ampere
Silicon is a/an _______
- (a)
conductor
- (b)
insulator
- (c)
semiconductor
- (d)
superconductor
Ampere second could be the unit of:
- (a)
Power
- (b)
Conductance
- (c)
Energy
- (d)
Charge
Which factors will both increase the resistance of a wire in a circuit?
- (a)
size of wire temperature of wire longer lower - (b)
size of wire temperature of wire shorter lower - (c)
size of wire temperature of wire thicker higher - (d)
size of wire temperature of wire thinner higher
Which circuit shows the correct positions for the fuse and the switch in the lighting circuit of a house? (Where L = live wire N = neutral wire)
- (a)
- (b)
- (c)
- (d)
A length of resistance wire is used as a resistor in a simple circuit
Four separate changes are made to the wire. Which change will not reduce the value of the resistance of the wire?
- (a)
It is covered in an insulating sleeve
- (b)
Its cross-sectional area is increased.
- (c)
Its length is decreased.
- (d)
Its temperature is decreased.
The metal case of an electric heater is earthed. The plug to the heater contains a 5 A fuse. There is a current of 4 A when the heater works normally. The cable to the heater becomes so worn that the live wire makes electrical contact with the case. What happens?
- (a)
The current flows to earth and the fuse is not affected.
- (b)
The fuse melts and switches off the circuit.
- (c)
The metal case becomes live and dangerous
- (d)
The metal case becomes very hot.
In the following circuits, heat produced in the resistor or combination of resistors connected to a 12 V battery will be
- (a)
same in all the cases
- (b)
minimum in case (i)
- (c)
maximum in case (ii)
- (d)
maximum in case (iii)
A current of 1A is drawn by a filament of an electric bulb. Number of electrons passing through a cross section of the filament in 16 seconds would be roughly
- (a)
1020
- (b)
1016
- (c)
1018
- (d)
1023
Identify the circuit in which the electrical components have been properly connected
- (a)
(i)
- (b)
(ii)
- (c)
(iii)
- (d)
(iv)
In an electrical circuit three incandescent bulbs A, B and C of rating 40 W, 60 Wand 100 W respectively are connected in parallel to an electric source. Which of the following is likely to happen regarding their brightness
- (a)
Brightness of all the bulbs will be the same
- (b)
Brightness of bulb A will be the maximum
- (c)
Brightness of bulb B will be more than that of A
- (d)
Brightness of bulb C will be less than that of B
Unit of electric power may also be expressed as
- (a)
volt ampere
- (b)
kilowatt hour
- (c)
watt second
- (d)
joule second
Number of joules in 1 kwh is
- (a)
3.6 x 107
- (b)
3.6 x 106
- (c)
3.6 x 105
- (d)
3.6 x 104
The equivalent resistance between points X and Y is 1 Ω
- (a)
3Ω
- (b)
1Ω
- (c)
6Ω
- (d)
9Ω
The resistance R of a device varies with temperature T as R = a + bT + c/T2.Where a, band c are positive constant The correct representation of the variation is
- (a)
- (b)
- (c)
- (d)
The minium resistance that can be obtained using five resistors each of value 0.5 Ω.
- (a)
1Ω
- (b)
0.5Ω
- (c)
0.2Ω
- (d)
0.1Ω
An ideal voltmeter of IV has the resistance equal to
- (a)
zero
- (b)
infinite
- (c)
unity
- (d)
none of these
n equal resistors are first connected in series and then connected in parallel. What is the ratio of the resultant resistances in the two arrangements?
- (a)
n-1
- (b)
n-3
- (c)
n
- (d)
n2