A rocket with a lift off mass 3.5×10⁴ kg is blast upward with an initial acceleration of 10 m/s². Then, the initial thrust of the blasts is

 

1.  1.75×10⁵ N

 

2.  3.5×10⁵ N

 

3.  7.0×10⁵ N

 

4.  14.0 ×10⁵ N

 

A step-down transformer is used on a 1000 V line to deliver 20 A at 120 V at the secondary coil. If the efficiency of the transformer is 80%, the current drawn from the line is

 

1.  3 A

 

2.  30 A

 

3.  0.3 A

 

4.  2.4 A

What kV potential is to be applied on X-ray tube so that minimum wavelength of emitted X-rays may be 1 Å (h = 6.6×10^-34 J-s)

 

Hydrogen atom excites energy level from fundamental state to n =3. Number of spectrum lines according to Bohr is

 

1.  4

 

2.  3

 

3.  1

 

4.  2

A black body at a temperature of 2600 K has the wavelength corresponding to maximum emission 1200Å. Assuming the moon to be perfectly black body the temperature of the moon, if the wavelength corresponding to maximum emission if 5000 Å is

 

The heat required to increase the temperature of 4 moles of a monoatomic ideal gas from 273 K to 473 K at constant volume is

 

A solid sphere rolls without slipping on the roof. The ratio of its rotational kinetic energy and its total kinetic energy is

 

6Ω and 12Ω resistors are connected in parallel. This combination is connected in series with a 10 V battery and 6Ω resistor. What is the potential difference between the terminals of the 12Ω resistor?

 

1.  4 V

 

2.  16 V

 

3.  2

 

4.  8 V

Charge passing through a conductor of cross section area A = 0.3m² is given by q = 3t² +5t+2 in coulomb, where t is in second. What is the value of drift velocity at t = 2s? (Given, n = 2×10²⁵/m³)

 

1.  0.77×10^-5 m/s