Question

A 100 watt, 220 volt lamp takes a current of

• A. 2.2 amp
• B. 55 amp
• C. 5/11 amp
• D. 1.1 amp

Hint:

Always simplify the fraction step-by-step.
Cancel out the zeros first: \(\frac{100}{220} = \frac{10}{22}\).
Then divide by 2 to get \(\frac{5}{11}\). This prevents calculation mistakes.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
We are given the power rating (\(100\text{ W}\)) and the operating voltage (\(220\text{ V}\)) of an electric lamp. We need to calculate the electric current flowing through it during normal operation.

Step 2: Key Formula or Approach:
The relationship between electric power (\(P\)), voltage (\(V\)), and current (\(I\)) is:
\[ P = V \cdot I \implies I = \frac{P}{V} \]

Step 3: Detailed Explanation:

• Given values:
Power (\(P\)) = \(100\text{ W}\)
Voltage (\(V\)) = \(220\text{ V}\)

• Substitute these values into the current formula:
\[ I = \frac{100}{220} \]

• Simplify the fraction by dividing the numerator and the denominator by their greatest common divisor, which is 20:
\[ I = \frac{100 \div 20}{220 \div 20} = \frac{5}{11}\text{ A} \]

• Expressed in decimals, this is approximately \(0.454\text{ A}\). However, the options are given in fractional form, matching \(\frac{5}{11}\text{ amp}\).


Step 4: Final Answer:
The current taken by the lamp is \(\frac{5}{11}\text{ amp}\).