بصریات اور جدید طبیعیات

Written by Dr. Hamza Farooq (Physics)

نیٹ · طبیعیات · 7 سوالات

نام: ____________________ تاریخ: ____________

An object is placed 30 cm from a concave mirror of focal length 10 cm. Where is the image formed?
- A 20 cm from the mirror
- B 15 cm from the mirror
- C 30 cm from the mirror
- D 7.5 cm from the mirror
An object is 20 cm in front of a convex lens of focal length 10 cm. What is the magnification?
- A -1
- B -2
- C +1
- D +2
X-rays are produced when:
- A A wire is heated slowly
- B Electrons are rapidly stopped by a metal target
- C Light passes through glass
- D Alpha particles hit a screen
What is the approximate energy of a photon of wavelength 500 nm?
- A 0.5 eV
- B 2.48 eV
- C 1.24 eV
- D 5 eV
The binding energy of a nucleus is found from its mass defect using:
- A E = 1/2 mv²
- B E = qV
- C E = hf
- D E = mc²
Which of these has the highest frequency?
- A Visible light
- B Microwaves
- C Radio waves
- D Gamma rays
Constructive interference of two waves occurs when the path difference is:
- A An odd multiple of half a wavelength
- B A quarter of a wavelength
- C A whole number of wavelengths
- D Zero only

جوابی کلید

1. B, 2. A, 3. B, 4. B, 5. D, 6. D, 7. C

From 1/v + 1/u = 1/f: 1/v = 1/10 - 1/30 = 2/30, so v = 15 cm.
The object at 2f gives an image at 2f on the other side, which is real, inverted and the same size, so m = -1.
When fast electrons decelerate in a metal target, they emit X-ray photons.
E (in eV) is about 1240 divided by the wavelength in nm, so 1240 / 500 = 2.48 eV.
The mass defect, multiplied by c squared, gives the binding energy.
Gamma rays are at the high-frequency, short-wavelength end of the electromagnetic spectrum.
When the path difference is n times the wavelength, the waves arrive in phase and reinforce each other.