Physics is the science that studies the nature and properties of matter and energy. It covers topics like motion, heat, light, sound, electricity, magnetism, and the structure of atoms.
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Question 621: Which of the following statements is (are) NOT true about the emission of the photoelectrons from metallic surfaces? i. all metallic surfaces emits the same number of photoelectrons in a given light ii. most metallic surfaces emit the same number of photoelectrons in visible and infra-red light iii. a metallic surface emits photoelectrons only if the frequency of the incident light is higher than its own characteristics threshold frequency
Options:
A) i only
B) ii only
C) i and ii
D) ii and iii
E) iii only
Show Answer
The correct answer is E .
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Question 622: The inside portion of part of a hollow metal sphere of diameter 20cm is polished. The portion will therefore form a
Options:
A) concave mirror of focal length 5cm
B) concave mirror of focal length 10cm
C) convex mirror of focal length 5cm
D) convex mirror of focal length 20cm
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The correct answer is A .
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Question 623: In a compound microscope
Options:
A) there is only one lens
B) the objective lens have a shorter focal length than the eyepiece which is convex
C) the objective lens has a longer focal length than the eyepiece which is convex
D) the objective lens has a shorter focal length than the eyepiece which is concave
E) the objective and the eyepiece are both convex and have the same focal length
Show Answer
The correct answer is B .
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Question 624:
In the Fig above, Current I passes through the combination, if the power dissipated in the 5 ohm resistor is 40W, then the power dissipated in the 10 ohm resistor is
Options:
A) 10W
B) 20W
C) 40W
D) 80
E) 100W
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The correct answer is B .
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Question 625:
A car moving at 20m/s with its horn blowing (f = 1200Hz) is chasing another car going at 15m/s. What is the apparent frequency of the horn as heard by the driver being chased?
Options:
A) 1.22KHz
B) 2.40KHz
C) 8.12KHz
D) 1.22Hz
Show Answer
The correct answer is A .
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Question 626:
I. A liquid boils when its saturated vapour pressure is equal to the external pressure
II. Dissolved substances in pure water lead to increase in the boiling point.
III. When the external pressure is increased, the boiling point increases.
IV. Dissolved substances in pure water decrease the boiling point.
Which combination of the above are peculiarities of the boiling point of a liquid?
Options:
A) I, II and III
B) I, II, III and IV
C) I, II and IV
D) II, III and IV
Show Answer
The correct answer is A .
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Question 627: a ray of light which strikes a glass slab from air at normal incidence passes through the slab
Options:
A) undeviated and undisplaced at a lower speed
B) deviated and undisplaced at a lower speed
C) deviated and displaced at a lower speed
D) undeviated and displaced at a faster speed
Show Answer
The correct answer is A .
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Question 628: A boy looks at the image of an object in a plane mirror. He observes two images, a main bright one and the other faint. The observed images result from
Options:
A) reflection only
B) refraction only
C) diffraction and interference
D) reflection and refraction
E) reflection and diffraction
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The correct answer is A .
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Question 629:
The volume of a stone having an irregular shape can be determined using?
Options:
A) meter rule
B) measuring cylinder
C) vernier calliper
D) micrometer screw gauge
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The correct answer is B .
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Question 630: Which of the following is NOT a part of a d.c. electric motor?
Options:
A) Field-magnet
B) Armature
C) Commutator
D) Transformer
Show Answer
The correct answer is D .