When light passes from a denser to a rarer medium at an angle greater than the critical angle, what happens?

The correct answer is B: Light undergoes total internal reflection. At critical angle θ_c, refracted ray becomes parallel to the interface. Beyond this angle, no refraction occurs; light completely reflects back into the denser medium (total internal reflection). This principle enables fiber optics.

Which of the following is NOT a vector quantity?

The correct answer is B: Temperature. Temperature is a scalar quantity as it has only magnitude. Displacement, velocity, and acceleration are vector quantities as they have both magnitude and direction.

A satellite orbits Earth at radius r with orbital velocity v. If the orbital radius is doubled, what happens to the orbital velocity?

The correct answer is C: It decreases by factor √2. From orbital mechanics: v = √(GM/r). If r becomes 2r, then v_new = √(GM/2r) = v/√2. Velocity decreases by factor √2.

A sound wave has a frequency of 440 Hz and travels at 330 m/s in air. What is its wavelength?

The correct answer is A: 0.75 m. Using v = fλ, where v = 330 m/s and f = 440 Hz. λ = v/f = 330/440 = 0.75 m.

Vitamin C deficiency causes?

The correct answer is B: Scurvy. Scurvy from Vitamin C deficiency.

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74 Questions 10 Topics Take Test

Showing 71–74 of 74 questions

Q.71 Easy Physics

A car accelerates from rest at 2 m/s². How long does it take to reach 20 m/s?

A 5 seconds

B 10 seconds

C 15 seconds

D 20 seconds

Correct Answer: B. 10 seconds

Explanation:

This problem uses the kinematic equation relating velocity, acceleration, and time for motion starting from rest.

Step 1: Identify the Given Values

We are given the initial velocity (starting from rest), final velocity, and acceleration. We need to find the time taken.

v_i = 0 \text{ m/s}, \quad v_f = 20 \text{ m/s}, \quad a = 2 \text{ m/s}^2, \quad t = ?

Step 2: Apply the Kinematic Equation

Using the equation that relates final velocity, initial velocity, acceleration, and time:

\[v_f = v_i + at\]

Substituting the values:

\[20 = 0 + (2)(t)\]

\[20 = 2t\]

t = \frac{20}{2} = 10 \text{ seconds}

The car takes 10 seconds to reach 20 m/s. The answer is (B) 10 seconds.

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Q.72 Easy Physics

Which of the following statements about gravitational force is correct?

A Gravitational force is repulsive in nature

B Gravitational force depends on the medium between objects

C Gravitational force is always attractive

D Gravitational force acts only between charged objects

Correct Answer: C. Gravitational force is always attractive

Explanation:

Gravitational force is always attractive, acts between any two masses, is independent of the medium, and is governed by Newton's law of universal gravitation.

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Q.73 Easy Physics

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.

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Q.74 Easy Physics