Q. In a metal, the path of motion of a free electron is
(a) straight line
(b) random
(c) circular
(d) parabolic
Answer : random
Q. A current of 1A is drawn by filament of an electric bulb. Number of electrons passing through the cross section of the filament in 16 seconds would be roughly
[NCERT Exemplar]
(a) 10²⁰
(b) 10¹⁶
(c) 10¹⁸
(d) 10²³
Answer: 10²⁰
Q. A constant current is passed through a uniform conductor. At any given segment of the conductor there is
(a) a net negative charge
(b) a net positive charge
(c) no net charge of any kind
(d) a net charge proportional to the volume of segment
Answer: no net charge of any kind
Q. If 5 coulombs of charge flows through a conductor in 2 seconds, then the number of electrons flowing through a conductor in one second approximately is
[NTSE]
(a) 30×10¹⁸
(b) 15.6×10¹⁸
(c) 6×10¹⁸
(d) 12×10¹⁸
Answer: 15.6×10¹⁸
Q. That potential at a point is 20 V. The work done in bringing a charge of 0.5 C from infinity to this point will be
(a) 20 J
(b) 10 J
(c) 5 J
(d) 40 J
Answer : 10 J
Q. The work done in moving an unit charge across two points in an electric circuit is a measure of
(a) current
(b) potential difference
(c) resistance
(d) power
Answer : potential difference
Q. No current flows between two charged identical bodies if they have same
(a) area of cross section
(b) potential
(c) charge
(d) Both (b) and (c)
Answer: Both (b) and (c)
Q. The expressions that relate (i) Q, I and t and (ii) Q, V and W respectively are (Here the symbols have their usual meanings)
(a) (i) I = Q/t (ii) W = V/Q
(b) (i) Q = It (ii) W = VQ
(c) (i) Q = I/t (ii) V = W/Q
(d) (i) I = Q/t (ii) Q = V/W
Answer: (i) Q = It (ii) W = VQ
Q. If the area of cross-section of resistance wire is halved, then its resistance becomes
(a) one-half
(b) 2 times
(c) one-fourth
(d) 4 times
Answer: 2 times
Q. Electrical resistivity of a given metallic wire depends upon
(a) its length
(b) its thickness
(c) its shape
(d) nature of the material
Answer : nature of the material
Q. A student carries out an experiment and plots the V-I graph of the three samples of nichrome wire with resistances R1, R2 and R3 respectively. Which of the following is true?
[NCERT Exemplar]
(a) R1 = R2 = R3
(b) R1 > R2 > R3
(c) R3 > R2 > R1
(d) R2 > R3 > R1
Answer: R3 > R2 > R1
Q. The resistivity does not change if[NCERT Exemplar]
(a) the material is changed
(b) the temperature is changed
(c) the shape of the resistor is changed
(d) both material and temperature are changed
Answer : the shape of the resistor is changed
Q. If the resistance of your body is 100000 ohm, what would be the current that flows in your body when you touch the terminals of a 12 volt battery?[NTSE]
(a) 10×10-5 A
(b) 14×10-5 A
(c) 12×10-5 A
(d) None of these
Answer: 12×10-5 A
Q. In which of the following cases Ohm’s law is not applicable?
(a) arc lamp
(b) insulator
(c) electrolytes
(d) metals
Answer : insulator
Q. Specific resistance of wire
(a) increases with increase in temperature
(b) decreases with increase in temperature
(c) is independent of temperature
(d) first increases then decreases with increase in temperature
Answer: increases with increase in temperature
Q. At very low temperature the resistance of some substance becomes zero, then the substance are called
(a) bad conductors
(b) semiconductors
(c) good conductor(d) superconductors
Answer : superconductors
Q. In home, electrical devices are connected in
(a) series
(b) parallel
(c) both series and parallel
(d) none of these
Answer : parallel
Q. If the potential difference across each register is same, then the resistor are connected in
(a) series
(b) parallel
(c) both series and parallel
(d) none of these
Answer : parallel
Q. A cell, a resistor, a key and ammeter are arranged as shown in the figure circuit diagrams of figure. The current recorded in the ammeter will be [NCERT Exemplar]
(a) maximum in (i)
(b) maximum in (ii)
(c) maximum in (iii)
(d) the same in all the cases.
Answer : the same in all the cases
Q. In an electric circuit three incandescent bulbs A, B and C of rating 40 W, 60 W and 100 W respectively are connected in parallel to an electric source. Which of the following is likely to happen regarding their brightness?[NCERT Exemplar]
(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.
Answer : Brightness of bulb B will be more than that of A
Q. Two LED bulbs of 12 W and 6 W are connected in series. If the current through 12 W bulb is 0.06 A the current through 6 W bulb will be[CBSE 2023]
(a) 0.04 A
(b) 0.06 A
(c) 0.08 A
(d) 0.12 A
Answer : 0.06 A
Q. 6 ohm and 12 ohm resistors are connected in parallel. This combination is connected in series with a 10 volt battery and 6 ohm resistor. What is the potential difference between the terminals of the 12 ohm resistors?[NTSE]
(a) 14 V
(b) 16 V
(c) 10 V
(d) 4 V
Answer : 4 V
Q. In normal use a current of 3.5 A flows through a hair dryer. Choose a suitable fuse from the following
(a) 3 A
(b) 5 A
(c) 10 A
(d) 30 A
Answer : 5 A
Q. If the current I through a register is increased by 100% (assume that temperature remains unchanged), the increase in power dissipated will be[NCERT Exemplar]
(a) 100%
(b) 200%
(c) 300%
(d) 400%
Answer : 300%
Q. The resistance of a resistor is reduced to half of its initial value. If other parameters of the electrical circuit remain unaltered, the amount of a produce in the register will become[CBSE 2023]
(a) four time
(b) two times
(c) half
(d) one fourth
Answer : two times
Q. An electric kettle consumes 1 kW of electric power when operated at 220 V. A fuse wire of what rating must be used for it?
[NCERT Exemplar]
(a) 1 A
(b) 2 A
(c) 4 A
(d) 5 A
Answer : 5 A
Q. A heating unit of an electric stove is rated at 880 W. It is connected to a power supply of 220 V, the current it will consume
(a) 2 A
(b) 6 A
(c) 4 A
(d) 8 A
Answer : 4 A
Q. In the following circuits, heat produced in the resistor or combination of resistors connected to a 12 V battery will be
[NCERT Exemplar]
(a) same in all the cases
(b) minimum in case (i)
(c) maximum in case (ii)
(d) maximum in case (iii)
Answer : maximum in case (iii)