A seismograph is used to detect: MCQ with Answer and Explanation

A seismograph is used to detect:
A. Magnetic field variations
B. Earthquakes
C. Atmospheric pressure changes
D. Sound waves in water
Answer: Option B
Solution (By JKSSB Mock Tests)
Seismograph detects and records ground motions caused by earthquakes, volcanic activity, or explosions. It measures seismic waves (P-waves, S-waves). Barometer detects pressure changes; hydrophone detects underwater sound; magnetometer detects magnetic fields. Memory tip: 'Seismo = earthquake (like seismology)'. This instrument-application question tests knowledge of geophysical tools, frequently examined in competitive exams. Always associate instrument names with their field of use: seismograph (geology), barometer (meteorology), etc.

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Practice More Physics Questions

Question #1
The velocity-time graph of a particle moving in a straight line is shown. The displacement of the particle from t=0 to t=4s is: [Graph: triangle from (0,0) to (2,10) to (4,0)]
A. 20 m
B. 10 m
C. 40 m
D. 30 m

Correct Answer: Option A


Explanation:
Displacement = area under velocity-time graph. The graph forms a triangle with base 4 s and height 10 m/s. Area = ½ × base × height = ½ × 4 × 10 = 20 m. Since velocity is always positive, displacement equals distance travelled. Graphical analysis is powerful: area gives displacement, slope gives acceleration. This triangle represents motion with uniform acceleration followed by uniform retardation. Exam tip: For piecewise linear v-t graphs, calculate area of each geometric segment separately. Such graph-based questions assess conceptual clarity in motion analysis.

This question belongs to: Science Physics
Question #2
A body moves along a straight line with v = 2t + 3. Acceleration after 2 s is
A. 2 m/s²
B. 7 m/s²
C. 5 m/s²
D. 3 m/s²

Correct Answer: Option A


Explanation:
a = dv/dt = 2, constant.

This question belongs to: Science Physics
Question #3
The resistance of a conductor is inversely proportional to its
A. Area of cross-section
B. Temperature
C. Length
D. Resistivity

Correct Answer: Option A


Explanation:
R ∝ 1/A.

This question belongs to: Science Physics