# Unseen Passage

For Class 4 to Class 12

# Current Electricity MCQ Class 12 Physics

Please refer to Chapter 3 Current Electricity MCQ Class 12 Physics with answers below. These multiple-choice questions have been prepared based on the latest NCERT book for Class 12 Physics. Students should refer to MCQ Questions for Class 12 Physics with Answers to score more marks in Grade 12 Physics exams. Students should read the chapter Current Electricity and then attempt the following objective questions.

## MCQ Questions Class 12 Physics Chapter 3 Current Electricity

The Current Electricity MCQ Class 12 Physics provided below covers all important topics given in this chapter. These MCQs will help you to properly prepare for exams.

Question. Combine three resistors 5 Q, 4.5 Q and 3 Q in such a way that the total resistance of this combination is maximum
(a) 12.5 Q
(b) 13.5 Q
(c) 14.5 Q
(d) 16.5 Q

A

Question. Sparking occurs when a load is switched off because the circuit has high
(a) resistance
(b) inductance
(c) capacitance
(d) impedance

B

Question. The filament of an electric bulb is made of
(a) carbon
(b) aluminium
(c) tungsten
(d) nickel

C

Question. When a metal conductor connected to left gap of a meter bridge is heated, the balancing point
(a) shifts towards right
(b) shifts towards left
(c) remains unchanged
(d) remains at zero

A

Question. In a lamp load when more than one lamp are switched on the total resistance of the load
(a) increases
(b) decreases
(c) remains same
(d) none of the above

B

Question. The resistivity of alloy manganin is
(a) Nearly independent of temperature
(b) Increases rapidly with increase in temperature
(c) Decreases with increase in temperature
(d) Increases rapidly with decrease in temperature

A

Question. Which method can be used for absolute measurement of resistances ?
(a) Lorentz method
(b) Releigh method
(c) Ohm’s law method
(d) Wheatstone bridge method

D

Question. The current which is assumed to be flowing in a circuit from positive terminal to negative, is called
(a) direct current
(b) pulsating current
(c) conventional current
(d) alternating current

C

Question. If the efficiency of a machine is to be high, what should be low ?
(a) Input power
(b) Losses
(c) True component of power
(d) kWh consumed
(e) Ratio of output to input

B

Question. A rheostat differs from potentiometer in the respect that it
(a) has lower wattage rating
(b) has higher wattage rating
(c) has large number of turns
(d) offers large number of tapping

B

Question. Drift velocity of electrons is due to
(a) motion of conduction electrons due to random collisions.
(b) motion of conduction electrons due to electric field E
(c) repulsion to the conduction electrons due to inner electrons of ions.
(d) collision of conduction electrons with each other.

B

Question. A thermistor has
(a) positive temperature coefficient
(b) negative temperature coefficient
(c) zero temperature coefficient
(d) variable temperature coefficient

C

Question. When a potential difference V is applied across a conductor at a temperature T, the drift velocity of electrons is proportional to
(a) V
(b) V
(c) T
(d) T

B

Question. Which of the following quantities remain the same in all parts of a series circuit ?
(a) Voltage
(b) Current
(c) Power
(d) Resistance

B

Question. The relaxation time in conductors
(a) increases with the increases of temperature
(b) decreases with the increases of temperature
(c) it does not depends on temperature
(d) all of sudden changes at 400 K

B

Question. One newton meter is same as
(a) one watt
(b) one joule
(c) five joules
(d) one joule second

B

Question. The example of non-ohmic resistance is
(a) diode
(b) copper wire
(c) filament lamp
(d) carbon resistor

A

Question. The insulation on a current carrying conductor is provided
(a) to prevent leakage of current
(b) to prevent shock
(c) both of above factors
(d) none of above factors

C

Question. What is the suitable material for electric fuse?
(a) Cu
(b) Constantan
(d) Nichrome

C

Question. Appliances based on heating effect of current work on
(a) only a.c.
(b) only d.c.
(c) both a.c. and d.c.
(d) None of these

C

Question. When potential difference is applied across an electrolyte, then Ohm’s law is obeyed at
(a) zero potential
(b) very low potential
(c) negative potential
(d) high potential

D

Question. Two bulbs of 500 W and 200 W rated at 250 V will have resistance ratio as
(a) 4 : 25
(b) 25 : 4
(c) 2 : 5
(d) 5 : 2

C

Question. Potentiometer is based on
(a) deflection method
(b) zero deflection method
(c) both (a) and (b)
(d) None of these

B

Question. In the case of direct current
(a) magnitude and direction of current remains constant
(b) magnitude and direction of current changes with time
(c) magnitude of current changes with time
(d) magnitude of current remains constan

A

Question. Three 60 W bulbs are in parallel across the 60 V power line. If one bulb burns open
(a) there will be heavy current in the main line
(b) rest of the two bulbs will not light
(c) all three bulbs will light
(d) the other two bulbs will light

D

Question. Sensitivity of potentiometer can be increased by
(a) increasing the e.m.f of the cell
(b) increasing the length of the potentiometer
(c) decreasing the length of the potentiometer wire
(d) None of these

B

Question. By increasing the temperature the resistance of a conductor
(a) increases.
(b) decreases.
(c) remains constant.
(d) initially increases then decreases.

A

Question. Which is the best conductor of electricity ?
(a) Iron
(b) Silver
(c) Copper
(d) Carbon

B

Question. A field of force can exist only between
(a) two molecules
(b) two ions
(c) two atoms
(d) two metal particles

B

Question. If a copper wire is stretched to make it 0.1 % longer. The percentage change in its resistance is
(a) 0.2 % increase
(b) 0.2% decrease
(c) 0.1 % increase
(d) 0.1 % decrease

A

Question. A cell of e.m.f E and internal resistance r is connected across a resistance r. The potential difference between the terminals of the cell must be
(a) E
(b) E/2
(c) E/4
(d) 3E/2

B

Question. Varistors are
(a) insulators
(b) non-linear resistors
(c) carbon resistors
(d) resistors with zero temperature coefficient

B

Question. A 50 V battery is connected across a 10 Ω resistor and a current of 4 .76 A flows. The internal resistance of the battery is
(a) 0.5 Ω
(b) 0.1 Ω
(c) 0.2 Ω
(d) 0.3 Ω

A

Question. The condition for the validity under Ohm’s law is that
(a) resistance must be uniform
(b) current should be proportional to the size of the resistance
(c) resistance must be wire wound type
(d) temperature at positive end should be more than the temperature at negative end

A

Question. Electric pressure is also called
(a) resistance
(b) power
(c) voltage
(d) energy

C

Question. Out of the following which is an insulating material ?
(a) Copper
(b) Gold
(c) Silver
(d) Paper

D

Question. With rise in temperature the resistance of pure metals
(a) increases
(b) decreases
(c) first increases and then decreases
(d) remains constant

A

Question. An instrument which detects electric current is known as
(a) voltmeter
(b) rheostat
(c) wattmeter
(d) galvanometer

D

Question. Which of the following material has nearly zero temperature co-efficient of resistance?
(a) Manganin
(b) Porcelain
(c) Carbon
(d) Copper

A

Question. Nichrome wire is an alloy of
(c) nickel and chromium
(d) copper and silver

C

Question. The resistance of a few meters of wire conductor in closed electrical circuit is
(a) practically zero
(b) low
(c) high
(d) very high

A

Question. Resistance of carbon filament lamp as the applied voltage increases.
(a) increases
(b) decreases
(c) remains same
(d) none of the above

B

Question. The resistance of the material depends on :
(a) temperature
(b) length of conductor
(c) area of cross-section
(d) All the above

D

Question. Temperature co-efficient of resistance is expressed in terms of
(a) ohms/°C
(b) mhos/ohm°C
(e) ohms/ohm°C
(d) mhos/°C

C

Question. Electric current originates from which part of an atom?
(a) nucleus
(b) entire atom acting as a unit
(c) positively charged protons
(d) negatively charged electrons

D

Question. The resistance of the wire varies inversely as:
(a) Area of cross section
(b) Resistivity
(c) Length
(d) Temperature

A

Question. When one of three series resistors is removed from a circuit and the circuit is reconnected, the current
(a) increases by half
(b) increases
(c) decreases by half
(d) None of the above

A

Question. The curve representing Ohms law is a:
(a) Linear
(b) cosine function
(c) Parabola
(d) Hyperbola

A

Question. What are the basic components of a simple electric circuit?
(a) energy source
(b) connecting wires
(c) switch
(d) All the above

D

Question. What is the most commonly used conductor in electronics?
(a) copper
(b) aluminium
(c) gold
(d) silver

A

Question. All the edges of a block with parallel faces are unequal. Its longest edge is twice its shortest edge. The ratio of the maximum to minimum resistance between parallel faces is
(a) 2
(b) 4
(c) 8
(d) indeterminate unless the length of the third edge is specified

B

Question. The internal resistance of a primary cell is 4W. It generates a current of 0.2 A in an external reistance of 21 W. The rate of chemical energy consumed in providing the current is
(a) 0.42 J s–1
(b) 0.84 J s–1
(c) 1 J s–1
(d) 5 J s–1

C

Question. Three equal resistors, connected across a source of e.m.f. together dissipate 10 watt of power. What will be the power dissipated in watts if the same resistors are connected in parallel across the same source of e.m.f.
(a) 10
(b) 10/3
(c) 30
(d) 90

D

Question. An electrical cable of copper has just one wire of radius 9 mm. Its resistance is 5 ohm. This single copper wire of the cable is replaced by 6 different well insulated copper wires each of radius 3 mm. The total resistance of the cable will now be equal to
(a) 7.5 ohm
(b) 45 ohm
(c) 90 ohm
(d) 270 ohm

A

Question. In an experiment to measure the internal resistance of a cell, by a potentiometer, it is found that the balance point is at a length of 2 m, when the cell is shunted by a 5 Ω resistance and is at a length of 3 m when the cell is shunted by a 10 Ω resistance. The internal resistance of the cell is then
(a) 1.5 Ω
(b) 10 Ω
(c) 15 Ω
(d) 1 Ω

B

Question. A wire of radius r and another wire of radius 2r, both of same material and length are connected in series to each other. The combination is connected across a battery. The ratio of the heats produced in the two wires will be
(a) 4.00
(b) 2.00
(c) 0.50
(d) 0.25

A

Question. Water boils in the electric kettle in 15 minutes after switching on. If the length of heating wire is decreased to 2/3 of its initial value, then the same amount of water will boil with the same supply voltage in
(a) 8 minutes
(b) 10 minutes
(c) 12 minutes
(d) 15 minutes

B

Question. The length of a given cylindrical wire is increased by 100%. Due to the consequent decrease in diameter the change in the resistance of the wire will be
(a) 100%
(b) 50%
(c) 300%
(d) 200%

C

Question. To get maximum current in a resistance of 3 ohms, one can use n rows of m cells (connected in series) connected in parallel. If the total number of cells is 24 and the internal resistance of a cell is 0.5 ohms then
(a) m = 12, n = 2
(b) m = 8, n = 3
(c) m = 2, n = 12
(d) m = 6, n = 4

A

Question. Each of the resistance in the network shown in fig. is equal to R. The resistance between the terminals A and B is

(a) R
(b) 5 R
(c) 3 R
(d) 6 R