Question

When an electric heater is switched on, the current \(i\) is plotted against time \(t\). Taking into account the variation of resistance with temperature, which of the following best represents the resulting curve?

• A. continuously decreasing curve
• B. straight line rise
• C. curve bending downward
• D. curve bending upward

Hint:

At constant voltage, \(i\propto1/R(T)\).

Answer 1

The Correct Option is A

Step 1: For heater, temperature increases with time.
Step 2: Metallic resistance increases with temperature: \[ R\uparrow \Rightarrow i=\frac{V}{R}\downarrow. \]
Step 3: Therefore current gradually decreases, not increases.
Step 4: Option (A) showing decreasing current is correct.