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प्रश्न
Electromagnetic induction means ______.
विकल्प
Charging of an electric conductor.
Production of magnetic field due to a current flowing through a coil.
Generation of a current in a coil due to relative motion between the coil and the magnet.
Motion of the coil around the axle in an electric motor.
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उत्तर
Electromagnetic induction means generation of a current in a coil due to relative motion between the coil and the magnet.
APPEARS IN
संबंधित प्रश्न
Electric field intensity in free space at a distance ‘r’ outside the charged conducting sphere of radius ‘R’ in terms of surface charge density ‘ a ’ is............................
(a)`sigma / in_0[R/r]^2`
(b)`in_0/sigma[R/r]^2`
(c)`R/r[sigma/in_0]^2`
(d)`R/sigma[r/in_0]^2`
The magnetic flux through a loop varies according to the relation Φ = 8t2 + 6t + C, where ‘C’ is constant, 'Φ' is in milliweber and 't' is in second. What is the magnitude of induced e.m.f. in the loop at t = 2 seconds.
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.
The phenomenon of electromagnetic induction is
A rectangular wire loop of sides 8 cm and 2 cm with a small cut is moving out of a region of uniform magnetic field of magnitude 0.3 T directed normal to the loop. What is the emf developed across the cut if the velocity of the loop is 1 cm s−1 in a direction normal to the
- longer side,
- shorter side of the loop?
For how long does the induced voltage last in each case?
Prove theoretically (electromagnetic induction) `e = (dphi)/(dt)`
A circular coil of cross-sectional area 200 cm2 and 20 turns is rotated about the vertical diameter with angular speed of 50 rad s−1 in a uniform magnetic field of magnitude 3.0 × 10−2T. Calculate the maximum value of the current in the coil.
Explain why, an electromagnet is called a temporary magnet.
The most suitable material for making the core of an electromagnet is:
(a) soft iron
(b) brass
(c) aluminium
(d) steel
State whether the following statement are true or false:
A generator works on the principle of electromagnetic induction.
Describe different ways to induce current in a coil of wire.
Welders wear special glass goggles while working. Why? Explain.
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.
A light metal disc on the top of an electromagnet is thrown up as the current is switched on. Why? Give reason.
Consider the energy density in a solenoid at its centre and that near its ends. Which of the two is greater?
Fill in the blanks by writing (i) Only soft iron, (ii) Only steel, (iii) Both soft-iron and steel for the material of core and/or magnet.
Transformer______.
Complete the following diagram of a transformer and name the parts labeled A and B. Name the part you have drawn to complete the diagram . What is the material of this part? In this transformer a step-up or step-down? Why?
List some of the practical applications of an electromagnet.
Why soft iron is preferred to be used as the core of the electromagnet of an electric bell?
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?
Observe the given figure of Fleming’s Right Hand Rule and write the labels of A and B correctly.
Write the two names in the following diagram.
Right hand thumb rule.
A closely wound circular coil of radius 0.02 m is placed perpendicular to the magnetic field. When the magnetic field is changed from 8000 T to 2000 T in 6 s, an emf of 44 V is induced in it. Calculate the number of turns in the coil.
An induced current of 2.5 mA flows through a single conductor of resistance 100 Ω. Find out the rate at which the magnetic flux is cut by the conductor.
A 50 cm long solenoid has 400 turns per cm. The diameter of the solenoid is 0.04 m. Find the magnetic flux linked with each turn when it carries a current of 1 A.
Shown in the figure below is a metre bridge set up with null deflection in the galvanometer. The value of the unknown resistance R is ______
Ansari Sir was demonstrating an experiment in his class with the setup as shown in the figure below.
A magnet is attached to a spring. The magnet can go in and out of the stationary coil. He lifted the Magnet and released it to make it oscillate through the coil.
Based on your understanding of the phenomenon, answer the following question.
What is the principle which Ansari Sir is trying to demonstrate?
If the sun radiates energy at the rate of 3.6 × 1033 ergs/sec the rate at which the sun is loosing mass is given by ______.
Sea turtles return to their birth beach many decades after they were born due to ______.
The working of a dynamo is based on the principle of
AB is a coil of copper wire having a large number of turns. The ends of the coil are connected with a galvanometer as shown. When the north pole of a strong bar magnet is moved towards end B of the coil, a deflection is observed in the galvanometer.
- State the reason for using galvanometer in the activity and why does its needle deflects momentarily when magnet is moved towards the coil.
- What would be observed in the galvanometer in a situation when the coil and the bar magnet both move with the same speed in the same direction? Justify your answer.
- State the conclusion that can be drawn from this activity.
Will there be any change in the momentary deflection in the galvanometer if number of turns in the coil is increased and a more stronger magnet is moved towards the coil?
OR
What is electromagnetic induction? What is observed in the galvanometer when a strong bar magnet is held stationary near one end of a coil of large number of turns? Justify your answer.
The charge will flow through a galvanometer of resistance 200Ω connected to a 400Ω circular coil of 1000 turns wound on a wooden stick 20 mm in diameter, if a magnetic field B = 0.012 T parallel to the axis of the stick decreased suddenly to zero, is near ______.
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:
