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Two small charged spheres A and B have charges of 10μC and 40μC respectively and are held at a separation of 90cm from each other. At what distance from A, electric field intensity would be zero?

a) 22.5 cm b) 18 cm c) 30 cm d) 36 cm Answer: c) 30 cm Solution: Electric field intensity = kq/x² Now the distance from B will... View Article

A cell of e.m.f E and internal resistance r is connected across a resistance r. The potential difference between the terminals of the cell must be

a) E b) E/2 c) 3E/4 d) 3E Answer: b) E/2 Solution: Current in the circuit, i = E/(r + r) = E/2r Potential difference across cell, V =... View Article

A particle of mass m is released on a smooth track in a vertical plane which transforms into a circular arc of radius R. Find the reaction force exerted at the bottom-most position.

a) 6mg b) 7mg c) 5mg d) 9mg Answer: a) 6mg Solution: The reaction force at the bottom is 6 mg... View Article

A ray of white light incident upon a glass prism is dispersed into various colour components. Which one of the following colours experiences the least refraction?

a) Red b) Yellow c) Orange d) Blue Answer: a) Red The light waves are refracted as they enter and leave the prism. The... View Article

Two small spheres, each of mass 0.1 gm and carrying same charge 10⁻⁹ C are suspended by threads of equal length from the same point. If the distance between the centres of the sphere is 3 cm, then find out the angle made by the thread with the vertical. (g = 10 m/s²) & tan⁻¹(1/100)=0.6⁰

Answer: 0.60 Solution: Tsinθ = Kq1q2/r2 Tcosθ = mg ⇒ tanθ = (Kq1q2/r2)/mg = [(9 x 109) x (10-19)2]/[(0.03)2 x 0.1 x 10-3 x 10] = 0.01... View Article

A body of mass m is placed on a rough surface with a coefficient of friction μ inclined at angle θ. If the mass is in limiting equilibrium, then

a) θ = tan-1 (m/μ) b) θ = tan-1 (μ) c) θ = tan-1 (μ/m) d) θ = tan-1 (1/μ) Answer: b) θ = tan-1 (μ) Solution: Given, mass of the body = m... View Article

The force [latex]overrightarrow{F}[/latex] experienced by a particle of charge q moving with a velocity [latex]overrightarrow{V}[/latex] in a magnetic field [latex]overrightarrow{B}[/latex] is given by [latex]overrightarrow{F}= q(overrightarrow{v}timesoverrightarrow{B})[/latex]. . Which pairs of vectors are always at right angles to each other?

a) b) c) d) Answer: a and b Solution: The pairs may have any angle between them.... View Article

A star that is emitting radiation at a wavelength of 5000 Å, is approaching the earth with a velocity of 1.5 x 104 m/s. The change in wavelength of the radiation as received on the earth is

(a) 25 Å (b) 100 Å (c) Zero (d) 2.5 Å Answer: (a) 25 Å Solution: Wavelength of the approaching star,... View Article

The logic gate realised from the circuit as shown in figure is (p and q are inputs and z is output)

a) XOR b) XOR c) NOR d) OR Answer: b) XOR Solution: P Q Y 0 0 0 0 1 1 1 0 1 1 1 0 Y = P ⊕ Q... View Article

Consider the situation given in the figure. The wire AB is slid on the fixed rails with a constant velocity. If the wire AB is replaced by a semicircular wire, the magnitude of the induced current will

a)decrease b) increases c)increase or decrease depending on whether the semicircle bulges towards the resistance or away from it d)remain same... View Article

Can the scalar product of two vectors be a negative quantity?

Answer: Yes, the scalar product of two vectors may be a negative quantity Solution: The scalar product of two vectors is |a||b|... View Article

The rate of cooling at 600k, if the surrounding temperature is 300K, is H. The rate of cooling at 900K is

a) 16/3 H b) 2 H c) 3 H d) (2/3) H Answer: a) 16/3 H Solution: By Stefan's law, rate of cooling, H ∝ (T4 - T04) H' = (16/3) H... View Article

An electron (mass=9.1×10⁻³¹kg) is sent into an electric field of intensity 9.1×10⁶ N/C. The acceleration produced is

a) 1.6 x 1018 m/s2 b) 1.6 x 106 m/s2 c) 1.6 x 10-18 m/s2 d) 1.6 x 10-6 m/s2 Answer: a) 1.6 x 1018 m/s2 Solution: a... View Article

A transformer of frequency 60 Hz and 120 V input has an 8:1 turn ratio. The frequency of the output is

a) 40 Hz b) 480 Hz c) 2 Hz d) 60 Hz Answer: d) 60 Hz Solution: The output frequency is 60 Hz... View Article

The ratio of time periods of α-particle and proton moving on a circular path in a uniform magnetic field is ___________.

a) 1: 2 b) 2: 1 c) 4: 1 d) 1: 4 Answer: b) 2: 1 Solution: The time period of revolution of a charged particle in a magnetic field is... View Article

An object falls from the top of a building that is 25 m high. Air resistance is negligible What is the speed of the object when it hits the ground?

A) 10 m/s B) 22 mis C) 25 m/s D) 625 m/s Answer: B) 22 m/s Solution: From the question: Initial velocity, u=0 Height of the building, h =25m... View Article

24 Dec 2021: UPSC Exam Comprehensive News Analysis

CNA 24 Dec 2021:- Download PDF Here TABLE OF CONTENTS A. GS 1 Related B. GS 2 Related POLITY 1. Understanding the Election Laws (Amendment) Bill,... View Article

23 Dec 2021: PIB Summary & Analysis

TABLE OF CONTENTS 1. Transient High Energy Pulses 2. Fifth Siddha Day 3. Conformity Assessment Scheme 1. Transient High Energy... View Article