A bulb rated 60 W-120 V is connected to 80 V mains. What is the current through the bulb

Options

A. `(1)/(3)A`
B. `(2)/(3)A`
C. `(5)/(3)`A
D. `(3)/(5)A`

Explanation

To find the current flowing through a bulb rated at 60 W and 120 V when connected to an 80 V mains supply, we can follow these steps:

### Step 1: Calculate the resistance of the bulb
The power rating (P) of the bulb is given as 60 W, and the voltage rating (V) is 120 V. We can use the formula for power:

\[ P = \frac{V^2}{R} \]

Rearranging this formula to find the resistance (R):

\[ R = \frac{V^2}{P} \]

Substituting the values:

\[ R = \frac{(120 \, \text{V})^2}{60 \, \text{W}} = \frac{14400 \, \text{V}^2}{60 \, \text{W}} = 240 \, \Omega \]

### Step 2: Calculate the current through the bulb when connected to 80 V
Now that we have the resistance, we can find the current (I) when the bulb is connected to an 80 V supply using Ohm's law:

\[ I = \frac{V}{R} \]

Substituting the values:

\[ I = \frac{80 \, \text{V}}{240 \, \Omega} = \frac{1}{3} \, \text{A} \]

### Final Answer
The current through the bulb when connected to an 80 V mains supply is:

\[ I = \frac{1}{3} \, \text{A} \quad \text{(or approximately 0.33 A)} \]

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