CBSE Class 10 Physics Electricity Worksheet Set B

Question. A wire of length /, made of material resistivity ρ is cut into two equal parts. The resistivity of the two parts are equal to,
(a) ρ
(b) \(\frac{\rho}{2}\)
(c) 2 ρ
(d) 4 ρ

Answer : A

Question. A coil in the heater consume power P on passing current. If it is cut into halves and joined in parallel, it will consume power
(a) P
(b) \(\frac{P}{2}\)
(c) 2P
(d) 4P

Answer : D

Question. Which of the following gases are filled in electric bulbs?
(a) Helium and Neon
(b) Neon and Argon
(c) Argon and Hydrogen
(d) Argon and Nitrogen

Answer : D

Question. To get 2 Ω resistance using only 6 Ω resistors, the number of them required is
(a) 2
(b) 3
(c) 4
(d) 6

Answer : B

Question. A current of 1 A 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

Answer : A

Question. The resistivity of insulators is of the order of
(a) 10-8 Ω-m
(b) 101 Ω-m
(c) 10-6 Ω-m
(d) 106 Ω-m

Answer : A

Question. What is the commercial unit of electrical energy?
(a) Joules
(b) Kilojoules
(c) Kilowatt-hour
(d) Watt-hour

Answer : C

Question. The resistivity does not change if 
(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 : C

Question. Electrical resistivity of any given metallic wire depends upon
(a) its thickness
(b) its shape
(c) nature of the material
(d) its length

Answer : C

Question. The resistance of hot filament of the bulb is about 10 times the cold resistance. What will be the resistance of 100 W-220 V lamp, when not in use?
(a) 48 Ω
(b) 400 Ω
(c) 484 Ω
(d) 48.4 Ω

Answer : C

Question. In an electrical circuit two resistors of 2 Ω and 4 Ω respectively are connected in series to a 6 V battery. The heat dissipated by the 4 Ω resistor in 5 s will be 
(a) 5 J
(b) 10 J
(c) 20 J
(d) 30 J

Answer : C

Question. Calculate the current flows through the 10 Ω resistor in the following circuit.
(a) 1.2 A
(b) 0.6 A
(c) 0.2 A
(d) 2.0 A

Answer : B

Question. 1 mV is equal to:
(a) 10 volt
(b) 1000 volt
(c) 10-3 volt
(d) 10-6 volt

Answer : C

Question. A cooler of 1500 W, 200 volt and a fan of 500 W, 200 volt are to be used from a household supply. The rating of fuse to be used is
(a) 2.5 A
(b) 5.0 A
(c) 7.5 A
(d) 10 A

Answer : D

Question. Coulomb is the SI unit of:
(a) charge
(b) current
(c) potential difference
(d) resistance

Answer : A

Question. What is the maximum resistance which can be made using five resistors each of 1/5 W? 
(a) 1/5 Ω
(b) 10 Ω
(c) 5 Ω
(d) 1 Ω

Answer : D

Question. A cell, a resistor, a key, and an ammeter are arranged as shown in the circuit diagrams. The current recorded in the ammeter will be
(a) maximum in (i)
(b) maximum in (ii)
(c) maximum in (iii)
(d) same in all the cases

Answer : D

Question. The heating element of an electric iron is made up of:
(a) copper
(b) nichrome
(c) aluminium
(d) iron

Answer : B

Question. Electric power is inversely proportional to
(a) resistance
(b) voltage
(c) current
(d) temperature

Answer : A

Question. The effective resistance between A and B is
(a) 4Ω
(b) 6Ω
(c) May be 10 Ω
(d) Must be 10 Ω

Answer : A

Fill in the Blanks :

Question. The SI unit of resistivity is ……… .
Answer: ohm-metre (Ω m)

Question. Presence of argon prolongs the life of ____________ .
Answer: Filament of electric bulb

Question. The temperature of a conductor is increased. The graph best showing the variation of its resistance is
Answer: Resistance is directly proportional to temperature of the conductor.

Question. If the potential difference across the ends of a conductor is doubled, the current flowing through it, gets ……… .
Answer: doubled

Question. Work done on unit charge is called as ____________ .
Answer: Potential difference

Question. Two resistors are in parallel when they have ____________ common points.
Answer: One

Important Questions for NCERT Class 10 Science Electricity

Question. Why is magnanin used for making standard resistors?
Answer: Magnanin being an alloy has a low temperature coefficient of resistance.

Question. Electric current flows through a metallic conductor from its one end A to other end B. Which end of the conductor is at higher potential? Why?
Answer: Current always flow from a higher potential to a lower potential end of the conductor. So end ‘A’ of the conductor is at a higher potential.

Question. Calculate the current in a circuit if 500 C of charge passes through it in 10 minutes.
Answer: Given: Q = 500 C, t = 10 min. = 10 × 60 = 600 s.

Question. An electric iron draws a cu,.ent of 0.6 A when the voltage is 100 volt Calculate the amount of electric charge flowing through it in one hour.
Answer: As we know, Q = I × t
∴ Q = 0.6 × 3600 = 2160 C

Question. What happens to resistance of a conductor when its area of cross-section is increased?
Answer: Resistance decreases as R ∝ \(\frac{1}{A}\).

Question. Define the term resistivity. 
Answer: The resistance offered by a wire of unit length and unit cross-sectional area is called resistivity. It is expressed in terms of ohm-metre (Q-m).

Question. Write S.I. unit of resistivity. 
Answer: Ohm-metre.

Question. How will the resistivity of a conductor change when its length is tripled by stretching it?
Answer: The resistivity of a metallic conductor does not depend on the length of the wire, so it will remain same.

Question. Name the charge responsible for the conduction in a conductor?
Answer: Electron.

Question. What is ohm? Define it.
Answer: One ohm is that resistance offered by the wire carrying 1A of current when IV is applied across its ends.

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