Gamma rays have MCQ with Answer and Explanation

Gamma rays have
A. Highest penetrating power
B. Highest ionising power
C. Greatest mass
D. Greatest charge
Answer: Option A
Solution (By JKSSB Mock Tests)
Gamma rays are EM waves, no mass/charge, highly penetrating, least ionising. Alpha has highest ionising power.

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Practice More Physics Questions

Question #1
The focal length of a concave mirror is 15 cm. The radius of curvature is
A. 15 cm
B. 45 cm
C. 30 cm
D. 7.5 cm

Correct Answer: Option C


Explanation:
For spherical mirrors, R = 2f. So R = 2 × 15 = 30 cm. Sign convention: for concave mirror, f and R are negative by Cartesian convention, but magnitude 30 cm. So 30 cm is correct.

This question belongs to: Science Physics
Question #2
The pressure at the bottom of a tank of water of depth 10 m (ρ=1000, g=10) is
A. 100000 Pa
B. 1000 Pa
C. 10 Pa
D. 100 Pa

Correct Answer: Option A


Explanation:
P = ρgh = 1000×10×10 = 100,000 Pa = 100 kPa.

This question belongs to: Science Physics
Question #3
When a source of sound moves towards a stationary observer, the apparent frequency:
A. Increases
B. Decreases
C. Becomes zero
D. Remains same

Correct Answer: Option A


Explanation:
This is the Doppler effect: when source moves toward observer, wavefronts compress, decreasing wavelength, thus increasing apparent frequency (f' = f·v/(v - v_s), where v is sound speed, v_s source speed). Conversely, receding source decreases frequency. This applies to all waves (light, sound). Memory aid: 'Approaching = higher pitch (frequency); Receding = lower pitch'. Competitive exams often test qualitative understanding before formula application. Always identify motion direction relative to observer for sign conventions in numerical problems.

This question belongs to: Science Physics