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प्रश्न
Write Fleming’s right hand thumb rule with the help of diagram.
Write Fleming’s right-hand thumb rule.
Explain the right-hand thumb rule with the help of a diagram.
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उत्तर
If a current-carrying straight conductor is held in our right hand such that the thumb points towards the direction of the current, then the curled fingers around the conductor will give the direction of the magnetic field.
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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`
State Fleming’s right-hand rule.
State three differences between direct current and alternating current.
Two circular coils A and B are placed closed to each other. If the current in the coil A is changed, will some current be induced in the coil B? Give reason.
When an electric current is passed through any wire, a magnetic field is produced around it. Then why an electric iron connecting cable does not attract nearby iron objects when electric current switched on through it?
State three ways in which the strength of an electromagnet can be increased.
Name two devices in which electromagnets are used and two devices where permanent magnets are used.
What is an electromagnet? Describe the construction and working of an electromagnet with the help of a labelled diagram.
Write some of the important uses of electromagnets.
The most suitable material for making the core of an electromagnet is:
(a) soft iron
(b) brass
(c) aluminium
(d) steel
The coil of a moving-coil galvanometer keeps on oscillating for a long time if it is deflected and released. If the ends of the coil are connected together, the oscillation stops at once. Explain.
A conducting rod is moved with a constant velocity v in a magnetic field. A potential difference appears across the two ends _____________ .
The switches in figure (a) and (b) are closed at t = 0 and reopened after a long time at t = t0.
(a) The charge on C just after t = 0 is εC.
(b) The charge on C long after t = 0 is εC.
(c) The current in L just before t = t0 is ε/R.
(d) The current in L long after t = t0 is ε/R.
A conducting square loop having edges of length 2.0 cm is rotated through 180° about a diagonal in 0.20 s. A magnetic field B exists in the region which is perpendicular to the loop in its initial position. If the average induced emf during the rotation is 20 mV, find the magnitude of the magnetic field.
Figure shows a wire sliding on two parallel, conducting rails placed at a separation l. A magnetic field B exists in a direction perpendicular to the plane of the rails. What force is necessary to keep the wire moving at a constant velocity v?
The following diagram shows a fixed coil of several turns connected to a center zero galvanometer G and a magnet NS which can move in the direction shown in the diagram.
- Describe the observation in the galvanometer if
- The magnet is moved rapidly,
- The magnet is kept still after it has moved into the coil
- The magnet is then rapidly pulled out the coil.
- How would the observation in (i) of part (a) change if a more powerful magnet is used?
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.
D.C. motor ______.
Name the following diagram and explain the concept behind it.
Draw a labelled diagram to show how an electromagnet is made.
List two ways of increasing the strength of an electromagnet if the material of the electromagnet is fixed.
Which of the following scientist invented the rule of electromagnetic induction?
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.
A coil of 200 turns carries a current of 0.4 A. If the magnetic flux of 4 mWb is linked with each turn of the coil, find the inductance of the coil.
Using Lenz’s law, predict the direction of induced current in conducting rings 1 and 2 when the current in the wire is steadily decreasing.
An alternating emf of 0.2 V is applied across an L-C-R series circuit having R = 4Q, C = 80µF, and L = 200 mH. At resonance the voltage drop across the inductor is
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 ______
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Which of the following instruments works by electromagnetic induction?
A coil of one turn is made of a wire of certain length and then from the same length, a coil of two turns is made. If the same current is passed in both the cases, then the ratio of the magnetic inductions at their centres will be:
A 0.4 m wire, stretched horizontally, carries an electric current of 15 A, in a magnetic field whose magnetic field intensity is 0.1 N/Am. What is the magnitude of the wire?
In the given circuit, initially switch S1 is closed and S2 and S3 are open. After charging of capacitor, at t = 0, S1 is open and S2 and S3 are closed. If the relation between inductance capacitance and resistance is L = 4CR2 then the time (in sec) after which current passing through capacitor and inductor will be same is ______ × 10-4 N. (Given R = ℓn(2)mΩ, L = 2mH)
Which type of force is experienced by a moving charge in a magnetic field?
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:
