# Archives

## Indian Air Force Day 2021

The Indian Air Force Day is celebrated on October 8th every year, to mark the date of establishment of the Bharatiya Vayu Sena. 8th October 2021... View Article

## Global Cybersecurity Index (GCI) 2020

In June 2021, the International Telecommunication Union (ITU) released the Global Cybersecurity Index 2020, a trusted reference that measures the... View Article

## COVAX [COVID-19 Vaccines Global Access]

The global vaccine alliance COVAX is in the news because of the ongoing COVID-19 pandemic and the vaccination drive conducted across the globe to... View Article

## 15 July 2021: The Hindu Analysis

UPSC Current Affairs Preparation: The Hindu Analysis Watch expert analysis of ‘The Hindu’ dated 15th Jul 2021. Important news and views to boost... View Article

## AIR Spotlight – PM’s Message to People to follow Covid Appropriate Behaviour

AIR Spotlight is an insightful programme featured daily on the All India Radio Newsonair. In this program, many eminent panelists discuss issues... View Article

## Holodomor

The Holodomor was a famine which killed millions of Ukrainians from 1932 to 1933 when it was under the control of the Soviet Union. The term... View Article

## A block of mass M is hanging by a string of negligible mass in a car. The speed of the wave in the string 60 m/s. Now the car is accelerated horizontally by an acceleration at the speed of wave in the string is 60.5 m/s. What is a in terms of g?

a) g/5 b) g/10 c) g/20 d) g/30 Answer (c) Speed of wave on string wherein, T is Tension in the string and μ is linear mass density... View Article

## In a semiconductor mobility of electron, i.e. drift velocity per unit applied electric field is 1.6 (S.I unit). Density of electrons is 1019/m3. (Neglect holes concentration). Resistivity of semiconductor is:

a) 0.4 Ωm b) 2 Ωm c) 4 Ωm d) 0.2 Ωm Answer: (a)... View Article

## A capacitor is formed by two square metal-plates of edge a, separated by a distance d. Dielectric of dielectric constants K is filled in the gap as shown in the figure. The equivalent capacitance is

a) b) c) d) Answer: (a) y/d = x/a …(1) After integrating, we get option 1 as an answer.... View Article

## A rod of acted by two equal forces as shown in the figure. The coefficient of thermal expansion of the rod is α and area of cross section is A. When the temperature the rod increased by Δ t. The length of the rod does not change. The young’s modulus Y will be.

a) b) c) d) Answer: (b) ...(1) ...(2) From (1) and (2) y=... View Article

## A uniform L shaped rod each of side A is held as shown in the figure. The angle θ such that the rod remains stable will be;

a) tan-1(1/2) b) tan-1(1/3) c) tan-1(2) d) tan-1(1) Answer: (b) Clockwise torque = anti clockwise torque θ = tan-1 (1/3)... View Article

## If length of resistance wire is increased by 0.5 % keeping the volume constant then change in resistance will be;

a) 0 % b) 1 % c) 0.5 % d) 2 % Answer: (b) R ∝ l2 New length = L + 0.5 % of L  = L+ 0.005 L  =1.005 L  It is... View Article

## Two coherent light sources having intensity I1 and I2. If the ratio of Imax/Imin is 6 : 1. Find I1/I2​​?

a) 16/9 b) 9/16 c) 4/1 d) 25/9 Answer: (d) On Simplifying above expression, we get (I1/I2) = 25/9... View Article

## If net force on charge kept at O is zero. The value of charge q is;

a) +Q /2 b) - Q /2 c) + Q/4 d) – Q/4 Answer (d) Net force of q = 0 q= - Q/4... View Article

## Value of i1 (Ampere) when switch is closed is.

a) 2 b) 5 c) 10 d) 1 Answer: (b) (V-20)/2 + (V-10)/4 = (V- 0)/2 V=10 , i=10/2 = 5A... View Article

## Light of wavelength λ1 = 340 nm and λ2 = 540 nm are incident on a metallic surface. If the ratio of the speed of the electrons ejected is 2. The work function of the metal is

a) 1 eV b) 1.85 eV c) 1.5 eV d) 2 eV Answer: (b) ----------(1) -------------(2) Substituting (2) in (1) we get hc/λ1 = Φ + 4(hc/λ2 - 4)... View Article

## In mixture 2 mole of He and 1 mole of Ar is present. Find $frac{(V_{RMS})_{He}}{(V_{RMS})_{Ar}}$ at 300 K.

a) 6.32 b) 1.58 c) 3.16 d) 10 Answer: (c) = 3.16... View Article

## Three blocks m, m and M are kept on a frictionless floor as shown in figure. The left most block is given velocity v towards right. All the collisions between the blocks are perfectly inelastic. The loss in kinetic energy after all the collisions is 5/6th of initial kinetic energy. The ratio of M/m will be:

a) 1/8 b) 1/4 c) 4 d) 2 Answer: (c) 6m = 2m+M =4m = M... View Article

## If temperature difference T1 – T2 is 120°C. The temperature difference between points A & B is

a) 30 b) 45 c) 60 d) 75 Answer: (b) Effective resistance between A and B is... View Article

## If current in a current carrying wire is 1.5A, number of free electrons per unit volume is 8 x1028m3 and area of cross section is 5 mm2 . Drift velocity of electrons will be

a) 0.02 mm/s b) 2 mm/s c) 0.2 mm/s d) None of these Answer: (a) i = e n A Vd (relation between i and Vd)... View Article