Electricity Worksheet-2
A. temperature B. material
C. cross-sectional area D. shape of cross-section.
A. varies with its length
B. varies with its cross-section
C. varies with its mass
D. is independent of length, cross-section and mass of the wire.
A. R_{1} + R_{2} B.
C. D.
A. R/4 B. R/2 C. R D. 2 R.
A. 14 Ω B. 10 Ω
C. (8/7) Ω D. between 2 Ω and 8 Ω
A. n B. 1/n^{2} C. n^{2} D. 1/n
A. R_{1} = 2R_{2} B. R_{2} = 2R_{1} C. R_{2} = 4R_{1} D. R_{1} = R_{2}
A. 100 W B. 50 W C. 25 W D. 400 W
A. 0.5 Ω B. 2 Ω C. 4 Ω D. 0.20 Ω
A. Rs. 100 B. Rs. 20 C. Rs. 25 D. Rs. 10.
Answer Key:
Explanation: Volume of the wire will not change when the wire is melted and recast. If l and A are the original length and area of cross-section and l’ and A’ are their corresponding values on recasting,
Al = A' l' or
Since
R’ (new resistance) = P l’/ A’
Or R’ = R/4.
Explanation: 1/2 +1/4 + 1/8 = (8/7) Ω
Explanation: For the same voltage (V),
and (as P = V^{2}/R)
Thus, or R_{2} = 2R_{1}
Explanation: Assuming that with the change in temperature, there is no variation in the resistance of bulb,
or
or
D
Explanation: Electric energy consumed = 10 × (40W × 10h) = 4000 Wh = 4 kWh
Cost of electricity consumption Rs. 4 × 2.50 = Rs. 10