PHYSICS
Electricity
1. The S I unit of potential difference is
(A) volt (V)
(B) ampere (A)
(C) coulomb (C)
(D) ohm meter (Ωm)
Ans: (A) volt (V)
2. The S I unit of electric current is
(A) ampere (A)
(B) ohm (Ω)
(C) volt (V)
(D) watt (W)
Ans: (A) ampere (A)
3. The rate of energy consumed in an electrical circuit is, electric
(A) current
(B) potential difference
(C) resistance
(D) power
Ans: (D) power
4. When three resistors of different resistance are connected in parallel in an electric circuit and switched on, then the quantity that remains the same in all the resistors is
(A) current
(B) potential difference
(C) resistance
(D) resistivity
Ans: (B) potential difference
5. The SI unit of resistivity is
(A) ohm-metre
(B) coulomb
(C) volt
(D) joule
Ans: (A) ohm-metre
6. The correct formula that shows the relationship between potential difference, electric current and resistance in an electric circuit is
(A) I = R/V
(B) I=VR
(C) V=I/R
(D) R=V/I
Ans: (D) R=V/I
7. A piece of metallic wire of resistance R is cut into 3 equal parts. These parts are then connected in parallel. If the total resistance of this combination is Rl, then the value of R : Rl is
(A) 1 : 3
(B) 9 : 1
(C) 1 : 9
(D) 3 : 1.
Ans: (B) 9 : 1
8. The resistance of a conductor is 27 Ω . If it is cut into three equal parts and connected in parallel, then its total resistance is
(A) 6 Ω
(B) 3 Ω
(C) 9 Ω
(D)27 Ω
Ans: (B) 3 Ω
9. SI unit of electric charge is
(A) coulomb
(B) ampere
(C) joule
(D) volt
Ans. : (A) coulomb
10. In an electric circuit to get an equivalent resistance Rs four resistors of 2Ω each are first connected in series. Later to get an equivalent resistance of Rp the same resistors are connected in parallel. Then the ratio of Rs/Rp is
(A) 16 : 1
(B) 2 : 1
(C) 4 : 1
(D) 8 : 1
Ans. : (A) 16 : 1
11. Ohm's law gives the relationship between
(A) potential difference and electric charge
(B) potential difference and resistance
(C) electric current and potential difference
(D) electric current and electric power
Ans: (C) electric current and potential difference
12. 0·75A current flows through an electric bulb when it is connected to a 220 V generator. Then the electric power of this bulb is
(A) 125 W
(B) 135 W
(C) 165 W
(D) 195 W
Ans. : (C) 165 W
13. If a device of 840W is to be used with 220V potential difference, then the rate of the fuse that is to be connected in this electrical circuit is
(A) 2A
(B) 4A
(C) 8A
(D) 12A
Ans. : (B) 4A
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