NEET Physics important Questions– Set 5 (Questions 41–50)

 

NEET Physics important Questions– Set 5 (Questions 41–50)

This is the final part of NEET Physics PYQ 2025 Series. Questions are concept-focused with explanations in easy Hinglish. MathJax enabled for formulas.

Q41. A particle moves in a circular path under the influence of a central force. The angular momentum:

remains constant
becomes zero
increases linearly
decreases exponentially

Correct: remains constant
Hinglish Explanation: Central force always acts towards center ⇒ torque zero ⇒ angular momentum conserved.

Q42. The de Broglie wavelength of an electron is \( \lambda = \frac{h}{mv} \). If velocity becomes double, wavelength becomes:

\( \lambda \)
\( \frac{\lambda}{2} \)
\( 2\lambda \)
\( \frac{\lambda}{4} \)

Correct: \( \frac{\lambda}{2} \)
Hinglish Explanation: Wavelength ∝ 1/velocity, so double speed ⇒ half wavelength.

Q43. A Carnot engine operates between 400 K and 300 K. Efficiency is:

25%
20%
30%
33%

Correct: 25%
\( \eta = 1 - \frac{T_c}{T_h} = 1 - \frac{300}{400} = 0.25 \)

Q44. The escape velocity from a planet is \( v_e = \sqrt{\frac{2GM}{R}} \). If radius is doubled, escape velocity becomes:

increases by \( \sqrt{2} \)
decreases by \( \sqrt{2} \)
doubles
becomes half

Correct: decreases by \( \sqrt{2} \)
Escape velocity ∝ \( \frac{1}{\sqrt{R}} \)

Q45. Capacitance of parallel plate capacitor is \( C = \frac{\epsilon_0 A}{d} \). If separation becomes 3d, capacitance becomes:

\( \frac{C}{3} \)
\( 3C \)
\( C \)
\( \frac{C}{9} \)

Correct: \( \frac{C}{3} \)
Capacitor ka gap badh gaya ⇒ capacitance kam ho gayi.

Q46. Magnetic force on a moving charge is \( F = qvB\sin\theta \). If velocity is parallel to magnetic field:

Maximum
Zero
Half
Doubled

Correct: Zero
\( \sin 0^\circ = 0 \) Isliye magnetic force nahi lagega.

Q47. A transformer has turns ratio 10:1. If input voltage is 200 V, output voltage is:

20 V
2000 V
2 V
100 V

Correct: 20 V
Step-down transformer ⇒ voltage / 10.

Q48. If a wire is stretched to double its length, its resistance:

doubles
becomes half
becomes four times
becomes one-fourth

Correct: becomes four times
Length ↑ ⇒ area ↓ ⇒ resistance ∝ \( L^2 \)

Q49. For a concave mirror, focal length is –20 cm. Image formed at infinity if object is at:

Focus
Pole
Centre
Beyond centre

Correct: Focus
Object at focus ⇒ rays become parallel ⇒ image at infinity.

Q50. If two resistors \( R_1 \) and \( R_2 \) are in parallel, total resistance is:

\( R_1 + R_2 \)
\( R_1 R_2 \)
\( \frac{R_1 R_2}{R_1 + R_2} \)
\( \frac{R_1 + R_2}{R_1 R_2} \)

Correct: \( \frac{R_1 R_2}{R_1 + R_2} \)
Parallel combination ka golden formula.

🔗 Set 1 | 🔗 Set 2 | 🔗 Set 3 | 🔗 Set 4

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