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?
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?
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At constant voltage, \(i\propto1/R(T)\).
Updated On: Jan 9, 2026
- continuously decreasing curve
- straight line rise
- curve bending downward
- curve bending upward
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The Correct Option is A
Solution and Explanation
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.
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.
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