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 721: The main reason for making the cover of a vacuum flask airtight is to prevent heat loss by
Options:
A) convection
B) conduction
C) radiation
D) evaporation
Show Answer
The correct answer is A .
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Question 722:
A thermocouple thermometer is connected to a millivoltmeter which can read up to 10mV. When one junction is in ice at 0°C and the other is steam at 100°C, the millivoltmeter reads 4mV. What is the maximum temperature which this arrangement can measure
Options:
A) 100C
B) 248C
C) 250C
D) 350C
Show Answer
The correct answer is C .
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Question 723: Three cells each of e.m.f. 1.5v and an internal resistance of 1.0 are connected in parallel across a load resistance of 2.67. Calculate the current in the load?
Options:
A) 0.26A
B) 0.41A
C) 0.50A
D) 0.79A
Show Answer
The correct answer is C .
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Question 724: An element and its isotope only differ in the number of
Options:
A) protons
B) electrons
C) ions
D) neutrons
Show Answer
The correct answer is D .
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Question 725:
The earth's gravitational field intensity at its surface is about
(G = 6.7 × 10Nm/kg, mass of the earth is 6 × 10kg, radius of the earth is 6.4 × 10m, g on the earth = 9.8m/s)
Options:
A) 6.7N/kg
B) 7.9N/kg
C) 8.0N/kg
D) 9.8N/kg
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The correct answer is D .
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Question 726: A spring of length 25cm is extended to 30cm by a load of 150N attached to one of its end, what is the energy stored in the spring?
Options:
A) 3750J
B) 2500J
C) 3.75J
D) 2.50J
Show Answer
The correct answer is C .
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Question 727:
Which of the units of the following physical quantities are derived?
I. Area
II. Thrust
III. Pressure
IV. Mass
Options:
A) I, II, III and IV
B) I, II, and III only
C) I, II, and IV only
D) I and IV only
Show Answer
The correct answer is B .
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Question 728: If the stress on a wire is 107NM-2 and the wire is stretched from its original length of 10.00 cm to 10.05 cm. The young's modulus of the wire is
Options:
A) 5 . 0 x 104 Nm-2
B) 5 . 0 x 105 Nm-2
C) 2 . 0 x 108 Nm-2
D) 2 . 0 x 109 Nm-2
Show Answer
The correct answer is D .
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Question 729:
Natural radioactivity consists of emission?
Options:
A) -particles and -rays
B) -particles and X-rays
C) -ray and X-rays
D) -particles and -rays and -rays
Show Answer
The correct answer is D .
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Question 730: A calibrated potentiometer is used to measure the e.m.f. of a cell because the
Options:
A) internal resistance of a cell is small compared with that of the potentiometer
B) potentiometer has a linear scale
C) potentiometer takes no current from the cell
D) resistance of the potentiometer is less than that of a voltmeter
Show Answer
The correct answer is C .