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प्रश्न
Welders wear special goggles or face masks with glass windows to protect their eyes from electromagnetic radiations. Name the radiations and write the range of their frequency.
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उत्तर
Welders wear special goggles to protect their eyes from Ultraviolet (UV) rays and Infrared (IR) rays. The range of UV rays is 8 × 1014 Hz to 5 × 1017 Hz. The range of IR rays is 3 × 1011 Hz to 4 × 1014 Hz.
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संबंधित प्रश्न
State Fleming’s right-hand rule.
A metal rod `1/sqrtpi `m long rotates about one of its ends perpendicular to a plane whose magnetic induction is 4 x 10-3 T. Calculate the number of revolutions made by the rod per second if the e.m.f. induced between the ends of the rod is 16 mV.
Name a common device that uses electromagnets.
In which of the following case does the electromagnetic induction occur?
The current is stopped in a wire held near a loop of wire .
A conducting rod is moved with a constant velocity v in a magnetic field. A potential difference appears across the two ends _____________ .
A transformer has 400 turns in the primary winding and 10 turns in the secondary winding. The primary e.m.f. is 250 V and the primary current is 2.0 A. calculate:
(a) The secondary voltage,
(b) The secondary current, assuming 100% efficiency.
Metal rings P and Q are lying in the same plane, where current I is increasing steadily. The induced current in metal rings is shown correctly in figure.
The instrument that use to defect electric current in the circuit is known as ____________.
A conducting bar of length L is free to slide on two parallel conducting rails as shown in the figure
Two resistors R1 and R2 are connected across the ends of the rails. There is a uniform magnetic field `vec"B"` pointing into the page. An external agent pulls the bar to the left at a constant speed v. The correct statement about the directions of induced currents I1 and I2 flowing through R1 and R2 respectively is:
A sheet is placed on horizontal surface in front of a strong magnetic pole. A force is needed to:
- hold the sheet there if it is magnetic.
- hold the sheet there if it is non-magnetic.
- move the sheet away from the pole with uniform velocity if it is conducting.
- move the sheet away from the pole with uniform velocity if it is both, non-conducting and nonpolar.
Choose the correct statement(s) from the options given below:
