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A step-down transformer has 50 turns on secondary and 1000 turns on the primary winding. If a transformer is connected to 220 V and 1 A AC source, what is the output current of the transformer?

1) 1/20 A 2) 20 A 3) 100 A 4) 2 A Answer: 2) 20 A Solution: Number of turns in the primary winding, Np= 1000 turns Number of turns in... View Article

Light with an energy flux of 18 w/m³ or Wm^–3 falls on a non-reflecting surface at normal to the surface. If the surface has an area of 20m². The average force exerted on the surface during 30 minutes is ______________

1) 6.48 x 105 N 2) 3.60 x 102 N 3) 1.2 x 10-6 N 4) 2.16 x 10-3 N Answer: 3) 1.2 x 10-6 N Solution: The average force by light on the... View Article

In the microwave oven, we use electromagnetic oscillators which produce electromagnetic waves in the wavelength range

1) 1mm to 10m 2) 0.7 μm to 1mm 3) 0.1 m to 1mm 4) 0.1 μm to 0.7 μm Answer: 3) 0.1 m to 1mm Solution: In the microwave oven,... View Article

Our eyes respond to wavelength ranging from

1) 400nm to 700nm 2) -∞ to +∞ 3) 1mm to 700nm 4) 700nm to 800nm Answer: 1) 400nm to 700nm Solution: Our eyes respond to... View Article

What is the ratio of velocities of light rays of wavelengths 4000^oA and 8000^oA in vacuum?

1) 1 : 2 2) 1 : 1 3) 2 : 1 4) cannot be determined Answer:2) 1 : 1 Solution: The velocity of all light rays is the same. Hence, the ratio... View Article

Unit of energy density of electromagnetic wave is _____________

1) Jm-3 2) Jm-2 3) Wm-2 4) None of these Answer: 1) Jm-3 Solution: Energy density = Energy/Volume = J/m3 = Jm-3... View Article

The frequency of electromagnetic wave having wavelength 25mm is ____________ Hz

1) 1.2 x 1010 2) 7.5 x 105 3) 1.2 x 108 4) 7.5 x 106 Answer: 1) 1.2 x 1010Hz Solution: Frequency= velocity/wavelength f =c/λ... View Article

Which of the following electromagnetic waves is used in telecommunication?

1) radio waves 2) visible radiations 3) ultraviolet rays 4) microwaves Answer: 4) microwaves Solution: Microwaves are used... View Article

Which of the following electromagnetic waves has the longest wavelength?

1) Radio waves 2) Infrared radiations 3) x rays 4) visible rays Answer: Radio waves Solution: Radio waves have the longest wavelength... View Article

In the electromagnetic spectrum, the visible light lies between

1) radiowaves and microwaves 2) ultraviolet rays and infrared rays 3) ultraviolet rays and x rays 4) infrared rays and microwaves... View Article

What is the wavelength of the range of electromagnetic waves?

1) 10-8 m to 1015 m 2) 10-15 m to 108 m 3) 10-15 m to 1015 m 4) 108 m to 1015 m Answer: 2) 10-15 m to 108 m Solution:... View Article

Electromagnetic waves used in medicine to destroy cancer cells

1) radio waves 2) infrared rays 3) gamma rays 4) ultraviolet rays Answer: 3) gamma rays Solution: Gamma rays are used in medicine to... View Article

An observer is at 2m from an isotropic point source of light emitting 40w power. The RMS value of electric due to the source at the position of the observer is_________

1) 5.77 x 10-8 Vm-1 2) 17.3 Vm-1 3) 57.7 x 10-8 Vm-1 4) 1.73 Vm-1 Answer: 2) 17.3 Vm-1 Solution: Intensity =... View Article

Electromagnetic waves travelling in a medium which has relative permeability 1.3 and relative permeability 2.14 speed of electromagnetic waves in this medium will be _________

1) 3.6 x 108 m/s 2) 1.8 x 108 m/s 3) 1.8 x 106 m/s 4) 13.6 x 106 m/s Answer: 2) 1.8 x 108 m/s... View Article

An electric charge oscillating with a frequency of 1kilo cycles/s can radiate electromagnetic waves of wavelength

1) 100km 2) 200km 3) 300km 4) 400km Answer: 3) 300km Solution: f = 1kilo cycles/s = 1 x 103 cycles/s = 103 Hz λ =... View Article

If a source is transmitting an electromagnetic wave of frequency 8.2 × 10⁶ Hz, then the wavelength of the electro-magnetic waves transmitted from the source will be

1) 36.6 m 2) 40.5 m 3) 42.3 m 4) 50.9 m Answer: 1) 36.6 m Solution: Wavelength, λ = c/ν = (3 x 108)/(8.2 ×... View Article