YNet StudyHub

1A parallel‑plate capacitor is charged to 12 V and then the plates are pulled apart until the capacitance is halved. What is the new voltage across the capacitor (assuming it is isolated)?

A 6 V B 12 V C 24 V D 48 V

2In a double‑slit experiment the slit separation is doubled while the screen distance and wavelength remain unchanged. How does the fringe spacing change?

A It halves B It doubles C It remains the same D It becomes four times larger

3A ray of light passes from air (n≈1.00) into glass (n≈1.50). Which statement is true?

A The speed of light increases B The wavelength increases C The frequency decreases D The speed of light decreases

4The half‑life of a radioactive isotope is 5 years. How much of a 80 g sample remains after 15 years?

A 10 g B 20 g C 40 g D 5 g

5A steel rod 0.5 m long is heated from 20 °C to 120 °C. Its coefficient of linear expansion is 12×10⁻⁶ °C⁻¹. What is the increase in length?

A 0.60 mm B 0.12 mm C 6.0 mm D 0.006 mm

6In a series RLC circuit at resonance, the current is maximum because:

A The inductive reactance equals the capacitive reactance B The resistance is zero C The voltage across the source is zero D The inductance is zero

7A photon has a frequency of 5×10¹⁴ Hz. What is its energy?

A 3.3×10⁻¹⁹ J B 6.6×10⁻¹⁹ J C 1.2×10⁻¹⁸ J D 2.0×10⁻¹⁹ J

8A thin convex lens forms a real image of a candle on a screen 40 cm from the lens. The object is 30 cm from the lens. What is the focal length of the lens?

A 12 cm B 24 cm C 48 cm D 60 cm

9In a digital communication system, which modulation technique conveys information by shifting the phase of the carrier?

A ASK B FSK C PSK D QAM

10The de‑Broglie wavelength of a 2.0×10⁻²⁵ kg particle moving at 200 m s⁻¹ is:

A 1.7×10⁻⁹ m B 1.7×10⁻⁸ m C 1.7×10⁻⁷ m D 1.7×10⁻⁶ m