37 Physics questions from real past papers, each with a written explanation. Physics is 20% of the paper - 36 of 180 questions.
If during circular motion, tangential velocity of a body becomes double then centripetal force becomes:
Explanation
Centripetal force varies as v^2 (Fc = mv^2/r). Doubling the tangential speed multiplies Fc by 2^2 = 4, so the force becomes four times. Answers like 'double' or 'one half' ignore the square dependence on velocity.
Under what condition an object will have zero displacement but non zero distance?
Explanation
In circular motion, after one full revolution the object returns to its starting point so displacement (vector from start to end) is zero while the distance travelled is the circumference (non-zero). Linear or random motion need not return to the start.
Which one of the following properties is not exhibited by the longitudinal waves?
Explanation
Polarization is a property of transverse waves (it involves orientation of oscillations). Longitudinal waves (oscillations parallel to propagation) can show interference, reflection and diffraction but not polarization.
The speed of sound in air is 332m/s. the speed of sound at 22oC will be:
Explanation
Speed of sound in air increases roughly by 0.6 m/s per °C from 0°C; V = 332 + 0.6×22 = 332 + 13.2 = 345.2 m/s. This gives option 345.2 m/s.
Astronomers calculate speed of dstant stars and galaxies using which of the following phenomena?
Explanation
The Doppler effect shifts spectral lines depending on radial velocity of astronomical objects; this shift is used to measure their speed. Beats and basic interference are not used for large-scale radial velocity measurements.
In a ripple tank, 40 waves pass through a certain point in 1 second. If the wavelength of the wave is 5 cm, then speed of the wave is:
Explanation
Wave speed v = fλ. Here f = 40 s⁻1 and λ = 0.05 m, so v = 40×0.05 = 2 m/s. The other choices are obtained from incorrect arithmetic or unit conversion.
In which process the entire of heat supplie to the gas is converted to the internal energy of the gas?
Explanation
In an isochoric (constant-volume) process no work is done (ΔV = 0), so any heat supplied changes only internal energy (ΔQ = ΔU). In isothermal ΔU = 0, and in adiabatic ΔQ = 0.
The internal energy of a system during an isothermal process:
Explanation
For an ideal gas in an isothermal process the temperature is constant, and internal energy depends only on temperature, so internal energy remains constant. It neither increases nor decreases.
If the potential at a point which is 1m from a charge is 1 volt, them the potential at a pont which is 2m from the same charge will be:
Explanation
Electric potential V due to point charge varies as 1/r (V = kQ/r). Doubling the distance halves the potential, so 1 V → 0.5 V at 2 m.
The values of electric intensity will due to the presence of dielectric medium:
Explanation
A dielectric reduces the effective electric field (electric intensity) within a capacitor for the same free charge because bound charges oppose the field; thus the field/PD is reduced if charge is held constant.
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The slope of distance – time graph will always be:
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If we drop an object, its initial velocity is zero. How far will it fall in time ‘t’?
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The newton-second is unit of:
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What is the speed of 2.9 kg metallic b ob at mean position of a simple pendulum, when release from its extreme position 0.5 m high? (g = 10m-2 )
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When the speed of your car is halved, by what factor does its kinetic energy decreases?
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Which one of the following force in non conservative force?
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The earth rotates on its axis once a day. Suppose, by dome process the earth contracts so that its radius is only half as large as at present, then how long the earth will take to complete its rotation?
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1 radian is equal to:
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In transmission from grid station, power losses are maximized by:
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The domestic electricity supply has a frequency of:
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PIV stands for:
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The wavelength associated with an electron is of the order of:
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Which photon carries the most energy?
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Which one of the following series lies in the ultraviolet region?
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The main difference between X-rays and γ rays is:
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There are initially 400 atoms in a radioactive sample. What of atoms after 3 half-life?
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Which using radiation theraphy, cancerous thyroid is treated with radioisotope:
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In capacitors, energy is stored in the form of:
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Ohm time’s farad is equivalent to:
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One kilowatt-hours is commonly termed as one commercial uniq of electric energy which is equal to:
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When a wire is compressed and its radius becomes 2R then its resistance will be:
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One of the following is an ohmicdevie:
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The change is resistance of metallic conductor at temperature below 0oC is:
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When current are flowing through two long parallel wires in same direction electric field between them is:
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Magnetic flux is maximum when angle between magnetic field and vector area is:
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Transformer is device which steps up or steps down the input:
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If a stationary bar magnet is places near a coil at rest so maximum lines of force passes through the coil, the galvanometer shows:
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