CLASS TEST-10
PHYSICS CHAPTER- 5, 6 & 7
CLASS – 10 M.M = 30
SEC – A [ 5 x 2= 10 ]
20
1. If frequency of a wave is 3 x 10 Hz, calculate its wavelength in meters.
2. A wave has wavelength and speed in air 4000 Å, 3 x 108 ms-1. Calculate its (i) frequency.
(ii) frequency in glass.
3. Calculate the wavelength in nanometer of yellow light of frequency 5.4 x 1014 Hz, if speed of light is 3 lac
km/sec.
4. Give one useful and one harmful effect of ultraviolet radiation on the human body.
5. Give the approximate range of wavelengths in vacuum associated with (i) UV rays (ii) visible light.
SEC – B [ 5 x 2= 10 ]
11. An object is placed at a distance of 12 cm from a convex lens of focal length 8 cm. Find :
(i) the position of the image (ii) nature of the image.
12. An erect, magnified and virtual image is formed when an object is placed between the optical centre and
principal focus of a lens.
(i) Name the lens.
(ii) Draw a ray diagram to show the formation of the image with the above stated characteristics
13. A lens forms an upright and diminished image of an object when the object is placed at the focal point of the
given lens. (i) Name the lens.
(ii) Draw a ray diagram to show the image formation.
14. Power of the two lenses are
(i) +5D, (ii) -2D. Name the lenses.
15. Figure shows a point source of light S, a convex lens L and a plane mirror M. The three are placed such that
rays of light from S return to it after reflection from M.
(i) What is the distance OS called
(ii) To which point (left of S, on S or right of S) will the rays return if M is moved to the left and brought in
contact with L ?
SEC – C [ 2+2+3+3 = 10 ]
16. (i) What do you understand by free vibrations of a body?
(ii) Why does the amplitude of a vibrating body continuously decreasing during damped
vibrations?
17. Displacement distance graph of two sound waves A and B, travelling in a medium, are as
shown in the given diagram Study the two sound waves and compare their :
(i) amplitudes
(ii) wavelengths
18. The diagram above shows a wire stretched over a sonometer. Stems of two vibrating
tuning forks A and B are touched to the wooden box of the sonometer. It is observed that the
paper rider (a small piece of paper folded at the centre) on the wire flies off when the stem of
vibrating tuning fork B is touched to the wooden box but the paper just vibrates when the
stem of vibrating tuning fork A is touched to the wooden box.
(i) Name the phenomenon when the paper ride just vibrated.
(ii) Name the phenomenon when the paper rider flies off.
(iii) Why does the paper rider fly when the stem of tuning fork B is touched to the box?
19. A person is standing at the sea shore. An observer on the ship which is anchored in
between a vertical cliff and the parson on the shore, fires a gun. The person on the shore
hears two sounds 2 and 3 seconds after seeing the smoke of the fired gun. If the speed of
sound in the air is 320 ms-1 then calculate:
(i) the distance between the observer on the ship and the person on the shore.
(ii) the distance between the cliff and the observer on the ship.
Yogesh Srivastava
Physics
CLASS TEST-10
Physics – Chapters: 5, 6 & 7
Class – 10
Maximum Marks = 30
Time: 45 minutes
SECTION – A [5 × 2 = 10]
1. If frequency of a wave is 3 × 10²⁰ Hz, calculate its wavelength in meters.
Answer: λ = c / f = 3 × 10⁸ / 3 × 10²⁰ = 1 × 10⁻¹² m
2. A wave has wavelength and speed in air 4000 Å, 3 × 10⁸ ms⁻¹. Calculate its (i) frequency (ii)
frequency in glass.
Answer: (i) λ = 4000 Å = 4 × 10⁻⁷ m; f = c / λ = 3 × 10⁸ / 4 × 10⁻⁷ = 7.5 × 10¹⁴ Hz
(ii) Frequency remains unchanged in glass = 7.5 × 10¹⁴ Hz
3. Calculate the wavelength in nanometer of yellow light of frequency 5.4 × 10¹⁴ Hz, if speed of light is
3 lakh km/s.
Answer: c = 3 × 10⁵ km/s = 3 × 10⁸ m/s
λ = c / f = 3 × 10⁸ / 5.4 × 10¹⁴ = 5.56 × 10⁻⁷ m = 556 nm
4. Give one useful and one harmful effect of ultraviolet radiation on the human body.
Answer: Useful: Helps in synthesis of Vitamin D
Harmful: Causes skin cancer or sunburn
5. Give the approximate range of wavelengths in vacuum associated with (i) UV rays (ii) visible light.
Answer: (i) UV rays: 10 nm to 400 nm OR 100A0 to 400 A0
(ii) Visible light: 400 nm to 700 nm OR Visible light: 400 nm to 800 nm
OR Visible light: 4000 A0 to 8000 A0
SECTION – B [5 × 2 = 10]
11. An object is placed at a distance of 12 cm from a convex lens of focal length 8 cm. Find: (i) the
position of the image (ii) nature of the image.
Answer: 1/f = 1/v - 1/u ⇒ 1/8 = 1/v + 1/12 ⇒ v = 24 cm
Nature: Real, Inverted and Enlarged
12. An erect, magnified and virtual image is formed when an object is placed between the optical
centre and principal focus of a lens.
(i) Name the lens. (ii) Draw a ray diagram.
Answer: (i) Convex lens
(ii) [Draw diagram]
13. A lens forms an upright and diminished image of an object when the object is placed at the focal
point of the given lens.
(i) Name the lens. (ii) Draw a ray diagram.
Answer: (i) Concave lens
(ii) [Draw diagram]
14. Power of the two lenses are (i) +5D, (ii) -2D. Name the lenses.
Answer: (i) +5D: Convex lens
(ii) -2D: Concave lens
15. Figure shows point source S, convex lens L and plane mirror M. Rays from S return after reflection.
(i) What is the distance OS called?
(ii) Where do rays return if M is brought in contact with L?
Answer: (i) focal length of convex lens OR focal length
(ii) Rays return to a point right of S
SECTION – C [2 + 2 + 3 + 3 = 10]
16. (i) What do you understand by free vibrations of a body?
(ii) Why does amplitude decrease during damped vibrations?
Answer: (i) Vibrations with natural frequency without external force.
(ii) Due to loss of energy from friction or resistance.
17. Displacement-distance graph of two sound waves A and B.
Compare their (i) amplitudes (ii) wavelengths.
Answer: (i) A has greater amplitude = 2:1
(ii) A has longer wavelength = 2:1
18. Tuning forks A and B touched to sonometer box; paper rider reacts differently.
(i) Name phenomenon when paper vibrates
(ii) Name phenomenon when paper flies
(iii) Why does paper fly with B?
Answer: (i) Forced vibrations
(ii) Resonance
(iii) Because natural frequency of wire matches Forced frequency of tuning fork B
19. Gun fired on ship between cliff and shore. Man on shore hears 2 sounds after 2s and 3s.
Speed of sound = 320 m/s.
(i) Distance between man and ship?
(ii) Distance between ship and cliff?
Answer: (i) d₁ = 320 × 2 = 640 m
(ii) 2d₂ + d1 = 320 x 3 = 960 m
d₂ = 160 m
Yogesh Srivastava
Physics
