Question

A coil of 12 Ω resistance is in parallel with a coil of 20 Ω
resistance. This combination is connected in series with a

third coil of 8 Ω resistance. If the whole circuit is connected

across a battery having an e.m.f. of 30 V and an internal

resistance of 2 Ω, calculate (a) the terminal voltage of the

battery and (b) the power in the 12 Ω coil.​

Answer 1

Answer:

A coil of 12 Ω resistance is in parallel with a coil of 20 Ω

third coil of 8 Ω resistance.

30 V and an internal

resistance of 2 Ω,

Explanation:

Equivalent resistance R' of the parallel combination of 12Ω,6Ω,and4Ω resistance is given by

1R'=112+112+16+14orR'=2Ω

Total nresistance of the circuit is R=1+5+2+2=10Ω

E = 20 - 8 = 12 V

a. Current in the circuit is I=ER=1210=1.2A

b. Combined resistance of 6Ωand4Ω in parallel is

6×46+4=2.4Ω

current in resistor of 12Ω coil is 2.412+2.4×1.2=0.2A

c. Potential difference across the 20 V battery is (20−1.2×1)

=18.8 V

Potential difference across the 8 V battery is (8+1.2×2)

=10.4 V