Advertisements
Advertisements
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.
Advertisements
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.
APPEARS IN
संबंधित प्रश्न
Explain why, the core of an electromagnet should be of soft iron and not of steel.
The direction of current in the coil at one end of an electromagnet is clockwise. This end of the electromagnet will be:
(a) north pole
(b) east pole
(c) south pole
(d) west pole
When current is 'switched on' and 'switched off' in a coil, a current is induced in another coil kept near it. What is this phenomenon known as?
How is the working of an electric bell affected, if alternating current be used instead of direct current?
Draw and label the diagram of a simple D.C. motor.
(a) Explain the rotation of the coil, giving a reason for your answer.
(b) How can you reverse the direction of rotation of the armature?
(c) How can you increase the speed of rotation of the motor?
Choose the correct option:
A conductor rod of length (l) is moving with velocity (v) in a direction normal to a uniform magnetic field (B). What will be the magnitude of induced emf produced between the ends of the moving conductor?
Write Fleming’s right hand thumb rule with the help of diagram.
An electron moves on a straight-line path XY as shown in the figure. The coil abcd is adjacent to the path of the electron. What will be the direction of the current, if any, induced in the coil?
What can produce a current in a coil even when the coil does not move?
