Each on the two strings of length 51.6 cm and 49.1 cm are tensioned separately by 20 N force. Mass per unit length of both the strings is same and equal to 1 gm^-1. When both strings vibrate simultaneously the number of beats is

• 5

• 7

• 8

• 8

Sodium has body centred packing.Distance between two nearest atoms is 3.7 A. The lattice parameter is

• 6.8 A

• 4.3 A

• 3.0 A

• 3.0 A

A block of mass M is attached to the lower end of a vertical strong. The string is hung from a ceiling and has to force constant value k. The mass is released from rest with the spring initially unstretched. The maximum extension produced in the length of the spring will be

• Mg/k

• 2Mg//k

• 4 Mg/ k

• 4 Mg/ k

The driver of a car travelling with speed 30 ms^-1 towards a hill sounds a horn of frequency 600 Hz. If the velocity of sound in air is 330 ms^-1, the frequency of reflected sound as heard by driver is

• 550 Hz

• 555.5 Hz

• 720 Hz

• 720 Hz

25.

A conducting circular loop is placed in uniform magnetic field 0.04 T with its plane perpendicular to the magnetic field. The radius of the loop starts shrinking at 2 mms^-1. The induced emf in the loop when the radius is 2 cm is 

• 3.2 π μ V

• 4.8 π μ V

• 0.8 π μ V

• 0.8 π μ V

A rectangular, a square a circular and an elliptical loop, all in the (x-y) plane, are moving out of a uniform magnetic field with a constant velocity, The magnetic field is directed along the negative z- axis direction. The induced emf, during the passage of these loops, out the field region, will not remain constant for

• the rectangular, circular and elliptical loops

• the circular and the elliptical loops

• only the elliptical loops

• only the elliptical loops

A wire of resistance 12 Ωm^-1 is bent to form a complete circle of radius 10 cm. The resistance between its two diametrically opposite point, A and B as shown in the figure, is

• 0.6 π Ω

•  3 π Ω

• 6 π Ω

• 6 π Ω

The electric field part of an electromagnetic wave in a medium is represented by
E_x = 0;

• moving along y direction with frequency 2π x 10⁶ Hz and wavelength 200 m.

• moving along x direction with frequency 10⁶ Hz and wavelength 200 m.

• moving along x direction with frequency 10⁶ Hz and wavelength 200 m
  
  

• moving along x direction with frequency 10⁶ Hz and wavelength 200 m
  
  

A student measures the terminal potential difference (V) of a cell (of emf and internal resistance r) as a function of the current (I) flowing through it. The slope and intercept of the graph between V and I, then respectively, equal

Three capacitors each of capacitance C and of breakdown voltage V are joined in series. The capacitance and breakdown voltage of the combination will be

• C/3, V/3

• 3C, V/3

• C/3, 3V

• C/3, 3V