Catch the false line on induction

Exercise and reference answers

Questions

1. False statement

   The induced current helps the change along.

   Statements

   1. Induced EMF equals the rate at which flux changes.
   2. The induced current opposes the change in flux.
   3. The induced current helps the change along.

2. False statement

   Energy stored in an inductor is L times I squared.

   Statements

   1. Energy stored in an inductor is L times I squared.
   2. Magnetic flux is measured in webers.
   3. Self induced EMF is minus L times dI by dt.

3. False statement

   Capacitive reactance rises with frequency.

   Statements

   1. Inductive reactance rises with frequency.
   2. Capacitive reactance rises with frequency.
   3. At resonance the two reactances are equal.

4. False statement

   At resonance the impedance is at its largest.

   Statements

   1. The LR time constant is L divided by R.
   2. Current reaches 63 per cent after one time constant.
   3. At resonance the impedance is at its largest.

Instructions

Each set of three lines about induced current holds one that is not true. Tap that line.

Explanation