Question

A battery and a variable resistor are in series with a small fan. A switch is closed, and the fan runs. When the variable resistor is moved slightly to the left, the fan slows down a little. When the variable resistor is moved slightly to the right, the fan speeds up a little. If the variable resistor in the circuit is set all the way to the right, what happens in the circuit?
I. The fan runs faster.
II. The voltage decreases.
III. The current increases.

• A. I only
• B. II only
• C. I and III only
• D. II and III only
• E. I, II, and III

Answer 1

The correct option is A I only

When the resistor is moving left , the resistance in the circuit increases and due to this current decreases , therefore fan slows down in speed . The reverse is happening when resistor moves right i.e. fan runs faster

When the resistor is moving right , the resistance in the circuit decreases and due to this current increases , therefore fan speed up.

If variable resistor is set to the right , the fan will run faster.