A tuning fork produce 2 beats when sounded with one oscillator of frequency 514 Hz, and produces 6 beats with the other oscillator of frequency 510 Hz. The frequency of tuning fork is

• 516 Hz

• 510 Hz

• 514 Hz

• 520 Hz

Colour of a star indicates its

• density

• distance

• energy

• temperature

If a liquid does not wet a solid surface, then its angle ofcontact is

• acute angle

• obtuse angle

• right angle

• None of these

To hear the echo in 1 s, the minimum distance of the source from the reflecting surface should be

• 28 m

• 18 m

• 19 m

• 165 m

If length of a simple pendulum increases by 300%, then its time period increases by

• 100 %

• 200 %

• 300 %

• 400 %

Sound waves produced in gas are

• longitudinal

• transversal

• stationary

• progressive

17.

When a force F is applied on a wire oflength L and radius r, extension produce is l. If same force F is applied on the same material wire of length 2 L and radius 2r, then extension will be

• l

• 2l

• l/2

• 4l

Intensity of a source of a 100 cd at a distance 2 m is

• 25 lux

• 50 lux

• 75 lux

• 150 lux

If tension of sonometer wire is made four times, then its frequency will change by a factor of

• 2

• 4

• 1/2

• 6

Which of the following has maximum specific heat?

• Water

• Alcohol

• Glycerene

• Oil