TOP
Main page
Books
Next
Physics MCQ Practice 15 — Science Foundation Course for Class 11 & 12
Answers
Score
Reset
1.
A body is moving with uniform velocity. The net force acting on it is:
(a) Zero
(b) Equal to mass
(c) Equal to velocity
(d) Infinite
Show Answer & Explanation
Correct Answer: (a) Zero
Explanation:
According to Newton's first law, net force is zero for uniform velocity
2.
The time period of a satellite orbiting close to Earth's surface is:
(a) 84 minutes
(b) 24 hours
(c) 12 hours
(d) 90 minutes
Show Answer & Explanation
Correct Answer: (a) 84 minutes
Explanation:
T = 2π√(R³/GM) ≈ 84 minutes for low Earth orbit
3.
The equivalent resistance when resistors of 2 Ω, 3 Ω and 6 Ω are connected in parallel is:
(a) 11 Ω
(b) 1 Ω
(c) 2 Ω
(d) 6 Ω
Show Answer & Explanation
Correct Answer: (b) 1 Ω
Explanation:
1/R = 1/2 + 1/3 + 1/6 = 1 → R = 1 Ω
4.
The fundamental frequency of a closed organ pipe of length 85 cm (v=340 m/s) is:
(a) 100 Hz
(b) 200 Hz
(c) 300 Hz
(d) 400 Hz
Show Answer & Explanation
Correct Answer: (a) 100 Hz
Explanation:
f = v/(4L) = 340 / (4×0.85) = 100 Hz
5.
The direction of induced emf is given by:
(a) Fleming’s left hand rule
(b) Fleming’s right hand rule
(c) Right hand thumb rule
(d) Left hand thumb rule
Show Answer & Explanation
Correct Answer: (b) Fleming’s right hand rule
Explanation:
Fleming’s right hand rule for induced current/emf
6.
A convex lens of focal length 20 cm is placed 30 cm from an object. The image distance is:
(a) 60 cm
(b) 12 cm
(c) 30 cm
(d) 15 cm
Show Answer & Explanation
Correct Answer: (a) 60 cm
Explanation:
Using lens formula:
1/v = 1/f + 1/u = 1/20 + 1/(-30) = 1/60
∴
v = +60 cm
(real image)
7.
The power factor in a purely resistive AC circuit is:
(a) 0
(b) 0.5
(c) 1
(d) -1
Show Answer & Explanation
Correct Answer: (c) 1
Explanation:
Phase difference zero → cosφ = 1
8.
The control rod in a nuclear reactor is made of:
(a) Uranium
(b) Cadmium
(c) Graphite
(d) Heavy water
Show Answer & Explanation
Correct Answer: (b) Cadmium
Explanation:
Cadmium absorbs neutrons to control reaction
9.
If the radius of a sphere is increased by 10%, the percentage increase in volume is:
(a) 10%
(b) 20%
(c) 30%
(d) 33.1%
Show Answer & Explanation
Correct Answer: (d) 33.1%
Explanation:
V ∝ r³ → (1.1)³ = 1.331 → increase of 33.1%
10.
The SI unit of permittivity of free space (ε₀) is:
(a) C²/N m²
(b) N m²/C²
(c) C/N m
(d) N/C ²
Show Answer & Explanation
Correct Answer: (a) C²/N m²
Explanation:
From Coulomb’s law: ε₀ = Q₁Q₂ / (4π F r²)