A 100 W bulb operates at 220 V. The current drawn by it is approximately: MCQ with Answer and Explanation

A 100 W bulb operates at 220 V. The current drawn by it is approximately:
A. 2.2 A
B. 4.5 A
C. 0.45 A
D. 0.22 A
Answer: Option C
Solution (By JKSSB Mock Tests)
Electric power P = VI. Thus I = P/V = 100 W / 220 V ≈ 0.4545 A ≈ 0.45 A. This direct application of power formula is fundamental in electricity. Memory tip: 'I = P/V for resistive loads'. Competitive exams frequently test such calculations with household appliance ratings. Always use consistent units (watts, volts, amperes). Note: This assumes purely resistive load (valid for incandescent bulbs); for motors or electronics, power factor may matter, but not at this level.

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Practice More Physics Questions

Question #1
The voltage of domestic AC supply in India is
A. 230 V, 50 Hz
B. 240 V, 60 Hz
C. 220 V, 50 Hz
D. 110 V, 60 Hz

Correct Answer: Option A


Explanation:
Standard in India: 230 V, 50 Hz (often 220-240).

This question belongs to: Science Physics
Question #2
A body moves with uniform acceleration. The graph between velocity and time is:
A. Straight line with positive slope
B. Straight line parallel to time axis
C. Parabola
D. Hyperbola

Correct Answer: Option A


Explanation:
Uniform acceleration means constant rate of change of velocity: a = dv/dt = constant. Thus v = u + at, a linear equation in t. Graph is straight line with slope = acceleration. Parallel to time axis (A) implies zero acceleration (constant velocity). Parabola (C) is for position-time under constant acceleration. Memory tip: 'v-t graph slope = acceleration; area = displacement'. This graph interpretation question tests kinematics fundamentals, frequently examined in competitive exams. Always link graph features to physical quantities: slope, area, intercepts have specific meanings in motion graphs.

This question belongs to: Science Physics
Question #3
A body weighs 100 N on Earth's surface. Weight at a height equal to Earth's radius is
A. 100 N
B. 50 N
C. 0 N
D. 25 N

Correct Answer: Option D


Explanation:
g' = g (R/(R+h))² = g (1/2)² = g/4. Weight = 100/4 = 25 N.

This question belongs to: Science Physics