We should not see the sun directly for a longer time because of the …………… radiations coming from the sunwhich may cause permanent blindness

Where should an object be placed in front of a convex lens of focal length 3cm to obtain a real image of sizethree times the size of the object, on the screen?

The power of a convex lens of focal length 10cm is ________

The maximum portion of the spherical surfaces from which refraction takes place is called ________________ 

Speed of light in any medium decreases with increase in the refractive index. In which medium the speed oflight is maximum?

Which of the following statements is not true for a machine?

The work done on an object does not depend on the _______ 

Kilowatt hour is the commercial unit of _____ 

a work of 1000 J is done on a body in 4 s, such that the diplacement is 20m. Calculate the force 

Calculate the K.E of a body of mass 5 kg and momentum 50 kgm/s

To detect obstacles in the path , bats produce _____ waves

A Man Standing 48 M Away from a Wall Fires a Gun Calculate the Time After Which an Echo is Heard. (The Speed of Sound in Air is 320 ms -1)

The repetition of sound heard in an empty room is called ______ 

One electronvolt is equal to _____ 

A physical quantity which has a unit is ___ 

In which of the following there is chemical to electrical change?

A wave passing from one medium to another, which of the following does not change

When  a satellite revolves around a planet, the work done by the planet is _____

The weight of a uniform half meter scale would act at ................ mark.

100 dyne cm is equal to ................ Nm.

Two balls A and B of masses 2m and 3m and their velocity 2v and 3v respectively . Find ratio of their momentum ?

What is the relation between velocity ratio (VR) and mechanical advantage (MA) for ideal machine ?

In a single fixed pulley , what is the velocity ratio ?

In an Electric cell which energy gets converted into which energy?

Which one of the following converts chemical energy to heat energy?

Which colour deviates most when white light is incident on prism?

The speed of light in air is 3 x 10^8 m s-1. Calculate the speed of light in glass. The refractive index of glass is 1.5.  

An object in a denser medium when viewed from a rarer medium appears to be raised. The shift is maximum for:      

When a ray of light from air enters a denser medium, it:    

Sound is which type of wave?

The human ear can detect sound in the frequency range 20Hz to 20000 Hz. If speed of sound is 330m/s, Find the wavelength, corresponding to the audible range of frequencies.

‘SONAR’ stands for?

The minimum distance between the source and the reflector in air, to hear an echo, is approximately

Select which one represents correct sequence of electromagnetic spectrum in their decreasing frequency

Which one is scattered least among them?

Which colour of scattered light has maximum intensity?