Dual Nature of Radiation and Matter — Physics STD 12 Science — Question

When the velocity of an electron increases, its de Broglie wavelength:

A tuning fork of frequency 480Hz is used to vibrate a sonometer wire having natural frequency 410Hz. The wire will vibrate with a frequency.

1. 410Hz
2. 480Hz
3. 820Hz
4. 960Hz.

A battery having e.m.f. 5V and internal resistance 0.5 W is connected with a resistance of 4.5 W then the voltage at the terminals of battery is

(a) 4.5 V

(b) 4 V

(c) 0 V

(d) 2 V

A metallic resistor is connected across a battery. If the number of collisions of the free electrons with the lattice is somehow decreased in the resistor (for example, by cooling it), the current will:

1. Increase.
2. Decrease.
3. Remain constant.
4. Become zero.

The threshold wavelength for photoelectric emission from a material is 5200 Å.  Photo-electrons will be emitted when this material is illuminated with monochromatic radiation from a

(a) 50 watt infrared lamp	(b) 1 watt infrared lamp
(c) 50 watt ultraviolet lamp	(d) Both (c) and (d)

Image of any object formed at the retina of human eye is :

For the study of the helical structure of nucleic acids, the property of electromagnetic radiation generally used is

(a) Reflection

(b) Interference

(c) Diffraction

(d) Polarization

Which of the following statements is not correct?

Tangent galvanometer is used to measure

(a) Steady currents	(b) Current impulses
(c) Magnetic moments of bar magnets	(d) Earth's magnetic field