Physics-
General
Easy
Question
Three charges are placed at the vertices of an equilateral triangle of side ‘a’ as shown in the following figure. The force experienced by the charge placed at the vertex A in a direction normal to BC is
- Zero
The correct answer is: Zero
Hence force experienced by the charge at A in the direction normal to BC is zero.
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A solid conducting sphere of radius a has a net positive charge 2Q. A conducting spherical shell of inner radius b and outer radius c is concentric with the solid sphere and has a net charge – Q. The surface charge density on the inner and outer surfaces of the spherical shell will be
A solid conducting sphere of radius a has a net positive charge 2Q. A conducting spherical shell of inner radius b and outer radius c is concentric with the solid sphere and has a net charge – Q. The surface charge density on the inner and outer surfaces of the spherical shell will be
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Charge on 
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When air is replaced by a dielectric medium of constant k, the maximum force of attraction between two charges separated by a distance
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Dielectric constant of pure water is 81. Its permittivity will be
Dielectric constant of pure water is 81. Its permittivity will be
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Four charges are arranged at the corners of a square ABCD, as shown in the adjoining figure. The force on the charge kept at the centre O is
Four charges are arranged at the corners of a square ABCD, as shown in the adjoining figure. The force on the charge kept at the centre O is
Physics-General
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An engine approaches a hill with a constant speed. When it is at a distance of 0.9 km it blows a whistle, whose echo is heard by the driver after 5 sec. If speed of sound in air is 330 m/s, the speed of engine is
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Physics-General
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The fundamental frequency of a closed pipe is 220 Hz. If 
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The fundamental frequency of a closed pipe is 220 Hz. If of the pipe is filled with water, the frequency of the first overtone of the pipe now is
Physics-General
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Two trains, one coming towards and another going away from an observer both at 4 m/s produce whistle simultaneously of frequency 300 Hz. Find the number of beats produced
Two trains, one coming towards and another going away from an observer both at 4 m/s produce whistle simultaneously of frequency 300 Hz. Find the number of beats produced
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An Indian submarine and an enemy submarine move towards each other during maneuvers in motionless water in the Indian ocean. The Indian submarine moves at 50 km/h, and the enemy submarine at 70 km/h. The Indian sub sends out a sonar signal (sound wave in water) at 1000 Hz. Sonar waves travel at 5500 km/h. What is the frequency detected by the Indian submarine
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A sound wave of wavelength 32 cm enters the tube at S as shown in the figure. Then the smallest radius r so that a minimum of sound is heard at detector D is
A sound wave of wavelength 32 cm enters the tube at S as shown in the figure. Then the smallest radius r so that a minimum of sound is heard at detector D is
Physics-General
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An engine is moving on a circular track with a constant speed. It is blowing a whistle of frequency 500 Hz. The frequency received by an observer standing stationary at the centre of the track is
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Physics-General
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Assertion : When a beetle moves along the sand with in a few tens of centimeters of a sand scorpion the scorpion immediately turn towards the beetle and dashes to it
Reason : When a beetle disturbs the sand, it sends pulses along the sands surface one set of pulses is longitudinal while other set is transverse.
Assertion : When a beetle moves along the sand with in a few tens of centimeters of a sand scorpion the scorpion immediately turn towards the beetle and dashes to it
Reason : When a beetle disturbs the sand, it sends pulses along the sands surface one set of pulses is longitudinal while other set is transverse.
Physics-General
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Assertion : On a rainy day sound travel slower than on a dry day.
Reason : When moisture is present in air the density of air increases.
Assertion : On a rainy day sound travel slower than on a dry day.
Reason : When moisture is present in air the density of air increases.
Physics-General
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Assertion : The basic of Laplace correction was that, exchange of heat between the region of compression and rarefaction in air is not possible.
Reason : Air is a bad conductor of heat and velocity of sound in air is large.
Assertion : The basic of Laplace correction was that, exchange of heat between the region of compression and rarefaction in air is not possible.
Reason : Air is a bad conductor of heat and velocity of sound in air is large.
Physics-General
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The displacement-time graphs for two sound waves A and B are shown in the figure, then the ratio of their intensities 
is equal to
The displacement-time graphs for two sound waves A and B are shown in the figure, then the ratio of their intensities is equal to
Physics-General
