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A resonance circuit having inductance and resistance 2 × 10^–4 H and 6.28 Ω respectively oscillates at 10 MHz frequency. The value of the quality factor of this resonator is________. [π = 3.14]

Answer: 2000 Given: R = 6.28 Ω f = 10 MHz L = 2 × 10-4 Henry We know that quality factor Q is given by ⇒ Q = XL / R =... View Article

Each side of a box made of metal sheet in cubic shape is ‘a’ at room temperature ‘T’, the coefficient of linear expansion of the metal sheet is ‘α’. The metal sheet is heated uniformly, by a small temperature ΔT, so that its new temperature is T+ΔT. Calculate the increase in the volume of the metal box:

a. 4/3 πa3αΔT b. 4πa3αΔT c. 3a3αΔT d. 4a3αΔT Answer: (c) Coefficient of volumetric... View Article

A cube of side ‘a’ has point charges +Q located at each of its vertices except at the origin where the charge is –Q. The electric field at the centre of cube is:

Answer: (c) We can replace –Q charge at origin by +Q and –2Q. Now due to +Q charge at every corner of the cube, the electric... View Article

03 Aug 2021: UPSC Exam Comprehensive News Analysis

August 3rd, 2021, PIB:- Download PDF Here TABLE OF CONTENTS A. GS 1 Related B. GS 2 Related POLITY AND GOVERNANCE 1. Amid protests, LS passes... View Article

02 Aug 2021: PIB Summary & Analysis

TABLE OF CONTENTS 1. e-RUPI 2. 12th Round of India-China Corps Commander Level Meeting 3. MSMEs Day 4. Pradhan Mantri Jan Vikas Karyakaram... View Article

The mass of the moon is about 1.2% of the mass of the earth. Compared to the gravitational force the earth exerts on the moon, the gravitational force the moon exerts on the earth

1) is the same 2) is smaller 3) is greater 4) varies with its phase Answer: 1) is the same Solution: The gravitational force of attraction... View Article

For a body to escape from earth, angle at which it should be fired is

1) 45o 2) > 45o 3) < 45o and 4) any angle Answer: 4) any angle Solution: The particle has to be fired with escape velocity,... View Article

If one moves from the surface of earth to moon, what will be the effect on its weight?

1) Weight of a person decreases continuously with height from the surface of earth 2) Weight of a person increases with height from the surface... View Article

Gravitational attraction on Earth on the stone of mass M is F_S. If the force on the hydrogen balloon of mass M located at the same space is F_B, then

1) FS > FB 2) FS < FB 3) FS = FB 4) FS = -FB Answer: 3) FS = FB Solution: Since mass M of the bodies is same, so gravitational... View Article

What is a period of revolution of the earth satellite? Ignore the height of satellite above the surface of the earth. Given, the value of gravitational acceleration g = 10 ms ^-2, radius of the earth Re = 6400 km. (take, π = 3.14)

1) 85 min 2) 156 min 3) 83.73 min 4) 90 min Answer: 3) 83.73 min Solution: Radius of earth RE = 6400 km = 6.4 x 106 m Time period of... View Article

There are two planets. The ratio of radius of the two planets is K but ratio of acceleration due to gravity of both planets is g. What will be the ratio of their escape velocity?

1) ( kg ) 1/2 2) ( kg ) -1/2 3) ( kg ) 2 4) ( kg ) -2 Answer: 1) ( kg ) 1/2 Solution: Escape velocity, --------(1) Acceleration due to... View Article

Weight of a body of mass m decreases by 1% when it is raised to height h above the earth’s surface. If the body is taken to a depth h in a mine, change in its weight is

1) 0.5% decrease 2) 2% decrease 3) 0.5% increase 4) 1% increase Answer: 1) 0.5% decrease Solution: Weight = mg g = GM/r2 gh = Gm/(r +... View Article

A geostationary satellite is revolving around the earth. To make it escape from gravitational field of earth, its velocity must be increased

1) 100 % 2) 41.4 % 3) 50 % 4) 59.6 % Answer: 2) 41.4 % Solution: ⇒ Centripetal force on satellite = Gravitional force between satellite... View Article

The period of a planet around sun is 27 times that of the earth. The ratio of radius of planet’s orbit to the radius of the earth’s orbit is

1) 4 2) 9 3) 64 4) 27 Answer: 2) 9 Solution: Kepler's third law of motion (Te2/Tp2) = (Re3/Rp3) Given, Tp = 27 Te (Te2/272 Te2) =... View Article

Rockets are launched in eastward direction to take advantage of

1) the clear sky on the Eastern side 2) the thinner atmosphere on this side 3) earth's rotation 4) earth's tilt Answer: 3) earth's rotation... View Article

If ρ is the density of the planet, the time period of near by satellite is given by

1) 2) 3) 4) Answer: 3) Solution: Time period of the satellite... View Article

A satellite is launched into a circular orbit of radius R around the earth. A second satellite is launched into an orbit of radius 4R. The ratio of their respective periods is

1) 4 : 1 2) 1 : 8 3) 8 : 1 4) 1 : 4 5) 1 : 2 Answer: 2) 1 : 8Solution: We have T2 ∝ R3 R1 = r R2 = 4r... View Article

If the radius of the earth were to shrink by one percent, its mass remaining the same, the acceleration due to gravity on the earth’s surface would

1) decrease 2) remain unchanged 3) increase 4) be zero Answer: 3) increase Solution: The acceleration due to gravity is given by g =... View Article

The escape velocity from the earth is 11 kms ^-1. The escape velocity from a planet having twice the radius and same mean density as that of earth is

1) 5.5 kms -1 2) 11 kms -1 3) 22 kms -1 4) None of these Answer: 3) 22 kms -1 Solution: The escape velocity of earth is given by... View Article

A body is projected with a velocity of 2 × 11.2 km/s from the surface of earth. The velocity of the body when it escapes the gravitational pull of the earth is

1) √3 × 11.2 km/s 2) 11.2 km/s 3) √2 × 11.2 km/s 4) 0.5 × 11.2 km/s 5) 2 × 11.2 km/s Answer: 2) 11.2... View Article

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