Question

The mutual inductance between a primary and secondary circuits is 0.5 H. The resistances of the primary and the secondary circuits are 20 ohms and 5 ohms respectively. To generate a current of 0.4 A in the secondary, current in the primary must be changed at the rate of

• A. 4.0 A/s
• B. 16.0 A/s
• C. 1.6 A/s
• D. 8.0 A/s

Answer 1

Answer: (A)

4.0 A/s

Answer 2

$e _ { 2 } = M \frac { d i _ { 1 } } { d t } \Rightarrow i _ { 2 } R _ { 2 } = M \frac { d i _ { 1 } } { d t } \Rightarrow 0.4 \times 5 = 0.5 \times \frac { d i _ { 1 } } { d t }$