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 691:

In the above circuit, The fuse wire melts when
Options:
A) K is Opened
B) K is closed
C) the 14 ohm resistor is doubled with k closed
D) the 6 ohm resistor is doubled with k closed
Show Answer
The correct answer is B .
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Question 692:
Particles of mass 10kg is fixed to the tip of a fan blade which rotates with angular velocity of 100rad. If the radius of the blade is 0.2m, the centripetalforce is?
Options:
A) 2N
B) 20N
C) 200N
D) 400N
Show Answer
The correct answer is B .
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Question 693:
Two mirrors of the same length are arranged as shown in the diagram. A ray of light NO strikes the system at O and emerges along PQ. The emergent ray has been deviated through
Options:
A) 220
B) 200
C) 210
D) 180
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The correct answer is D .
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Question 694:
A car of mass 800kg attains a speed of 25m/s in 20secs. The power developed in the engine is
Options:
A) 1.25 x 10W
B) 2.50x 10W
C) 1.25 x 10W
D) 2.50 x 10W
Show Answer
The correct answer is A .
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Question 695: The spectrum of white light consists of coloured lights arranged in the following order
Options:
A) blue, red, green, yellow, indigo, violet, orange
B) red, orange, yellow, green, blue, indigo, violet
C) red, orange, yellow, indigo, green, blue, violet
D) indigo, green, blue, violet, yellow, red, orange
E) yellow, blue, green, violet, orange, indigo, red
Show Answer
The correct answer is B .
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Question 696: in a pure semiconductor, the number of electrons in the conduction band is
Options:
A) less than the number of holes in the valence band
B) equal to the number of holes in the valence band
C) greater than the number of holes in the valence band
D) twice the number of holes in the valence band
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The correct answer is B .
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Question 697: The correct unit of energy density is?
Options:
A) kg m3 s-2
B) kg m2 s-2
C) kg m-3 s-2
D) kg m-1 s-2
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The correct answer is D .
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Question 698:
The lowest note emitted by a stretched string has a frequency of 40Hz. How many overtones are there between 40Hz and 180Hz?
Options:
A) 4
B) 3
C) 2
D) 1
Show Answer
The correct answer is B .
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Question 699: Three electric cells each of e.m.f 1.5V and internal resistance of 1.0 are connected in parallel across an external resistance of . Calculate the value of the current in the resistor
Options:
A) 0.5 A
B) 0.9A
C) 1.5A
D) 4.5A
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The correct answer is C .
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Question 700: The rise or fall of a liquid in a narrow tube is because of the
Options:
A) viscosity of the liquid
B) surface tension of the liquid
C) friction between the walls of the tube and the liquid
D) osmotic pressure of the liquid
Show Answer
The correct answer is C .