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 2611: A cell of internal resistance r supplies current to a 6.0Ω resistor and its efficiency is 75%. Find the value of r.
Options:
A) 4.5Ω
B) 1.0Ω
C) 8.0Ω
D) 2.0Ω
Show Answer
The correct answer is D .
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Question 2612:
An object is acted upon by a system of parallel three causing the object to be in state equilibrium. Which of the following statement is not correct
Options:
A) the resultant of the parallel forces is zero
B) the algebraic sum of all the moments of the forces is zero
C) all the parallel forces must be equal in magnitude and direction
D) the sum of forces in one direction must be equal to the sum of forces in the opposite direction
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The correct answer is C .
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Question 2613: The electromotive force obtained from a simple dynamo may be increased by
Options:
A) increasing the cross-sectional area of the coil
B) winding the coil on a soft-iron armature so as to decrease the magnetic flux through the coil
C) increasing the speed of rotation
D) making the field magnet longer
E) using low-resistance copper coils
Show Answer
The correct answer is C .
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Question 2614: The temperature at which the water vapour present in the air is just enough to saturate the air is the _______ point.
Options:
A) boiling
B) critical
C) dew
D) ice
E) steam
Show Answer
The correct answer is C .
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Question 2615:
A body was slightly displaced from its equilibrium position. Which one of the following is a condition for its stable equilibrium
Options:
A) an increase in the kinetic energy of the body
B) an increase in the potential energy of the body
C) a decrease in the kinetic energy of the body
D) an increase in the height of the body
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The correct answer is B .
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Question 2616: Which of the following types of motion is/are exhibited by a cylindrical drum rolling down an incline plane?
Options:
A) Random and rotational
B) Rotational and oscillatory
C) Rotational only
D) Translations only
E) Translational and rotational
Show Answer
The correct answer is E .
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Question 2617: What is the best method of demagnetizing a steel bar magnet?
Options:
A) Hammering
B) Heating it
C) Rough handling it
D) Solenoid method
Show Answer
The correct answer is D .
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Question 2618: Which of the following statements are true about the spring balance and the chemical balance? i. both are used to measure the mass of an object. ii. either of them may be used to measure the weight of an object. iii. the spring balance works on the principle of Hooke's law while the chemical balance works on the principle of moments. iv. a change in gravity does the readings of a spring balance but not that of a chemical balance.
Options:
A) i, and iv
B) ii and iii
C) ii and iv
D) i, ii and iii
E) i and iii
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The correct answer is C .
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Question 2619: Two forces A and B act at a point. If their resultant is [given by] (B - A) in the direction of B, then
Options:
A) A and B are equal
B) A is greater than B
C) the angle between A and B is 0°
D) the angle between A and B is 90°
E) the angle between A and B is 180°
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The correct answer is E .
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Question 2620: Radio waves belong to the class of wave whose velocity is about
Options:
A) 34m/s
B) 3 ×106m/s
C) 3 ×108m/s
D) 3 × 10-8m/s
Show Answer
The correct answer is C .