A ball is thrown vertically upward with initial velocity 20 m/s. What maximum height does it reach? (g = 10 m/s²)
A
10 m
B
20 m
C
30 m
D
40 m
Explanation:
At maximum height, v = 0. Using v² = u² - 2gh: 0 = 20² - 2(10)h. 20h = 400. h = 20 m.
Two capacitors of 2 μF and 3 μF are connected in series. What is the equivalent capacitance?
A
5 μF
B
1.2 μF
C
6 μF
D
0.5 μF
Correct Answer:
B. 1.2 μF
Explanation:
For capacitors in series: 1/C = 1/C₁ + 1/C₂ = 1/2 + 1/3 = 5/6. Therefore C = 6/5 = 1.2 μF.
Which of the following has the highest refractive index?
A
Air
B
Water
C
Diamond
D
Glass
Correct Answer:
C. Diamond
Explanation:
Refractive indices: Air ≈ 1, Water ≈ 1.33, Glass ≈ 1.5, Diamond ≈ 2.42. Diamond has the highest refractive index among these options.
A body moves in a circle of radius 5 m with constant speed 10 m/s. What is the centripetal acceleration?
A
2 m/s²
B
20 m/s²
C
50 m/s²
D
100 m/s²
Correct Answer:
B. 20 m/s²
Explanation:
Centripetal acceleration a = v²/r = (10)²/5 = 100/5 = 20 m/s².
A current of 5 A flows through a resistor for 10 seconds. How much charge passes through it?
A
0.5 C
B
2 C
C
50 C
D
500 C
Explanation:
Charge Q = I × t, where I = 5 A and t = 10 s. Q = 5 × 10 = 50 Coulombs.
An electron undergoes a transition from n=3 to n=1 in a hydrogen atom. Which series does this transition belong to?
A
Paschen series
B
Balmer series
C
Lyman series
D
Brackett series
Correct Answer:
C. Lyman series
Explanation:
The Lyman series involves transitions to n=1 from higher energy levels. Balmer series ends at n=2, Paschen at n=3, and Brackett at n=4.
An object of mass 2 kg experiences a net force of 10 N. If it starts from rest, what will be its velocity after traveling 5 m?
A
5 m/s
B
√50 m/s
C
10 m/s
D
√5 m/s
Explanation:
Using F = ma: a = F/m = 10/2 = 5 m/s². Using v² = u² + 2as: v² = 0 + 2(5)(5) = 50. v = √50 ≈ 7.07 m/s. Checking options again using work-energy: Work = KE; 10×5 = (1/2)(2)v²; v = 5√2 m/s. The closest correct approach gives v² = 50, so v = 5√2 m/s or approximately 7.07 m/s. Option B matches √50.
