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. R1 + R2 B.
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/n2 C. n2 D. 1/n
A. R1 = 2R2 B. R2 = 2R1 C. R2 = 4R1 D. R1 = R2
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.
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
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 = V2/R)
Thus, or R2 = 2R1
Explanation: Assuming that with the change in temperature, there is no variation in the resistance of bulb,
Explanation: Electric energy consumed = 10 × (40W × 10h) = 4000 Wh = 4 kWh
Cost of electricity consumption Rs. 4 × 2.50 = Rs. 10