Which of the following is a vector quantity?
What is the relation for magnetic field at the centre of a circular coil of radius r ?
A commutator changes the direction of current in the coil of
The magnetic field at a point due to current carrying conductor is directly proportional to
A. Current flowing through the conductor
B. Distance of the conductor
C. Resistance of the conductor
D. None of the above
Which of the following organs in the human body where the magnetic field produced is significant?
What are the constituents of Alnico?
The magnetic field lines due to straight wire carrying a current are-
Which of the following is incorrect?
A. Another name of field lines is lines of space
B. Neutral wire is always at zero potential
C. Heat loss in DC is less than AC
D. Electric fuse is a current generating device
‘An electric current always produces a magnetic field’ , The above statement is
Who first detected the presence of magnetic field in earth?
The power of an electric motor can be increased by
Which of following statement is not correct about electric fuse
A. It is always connected in live wire
B. It is always connected in the end of the circuit
C. Thinner the fuse wire, greater is its current capacity
D. Its current capacity must be less than the maximum current
Which of the following sentences is correct about Overloading
An electric fuse can prevent accidents arising from-
What capacity of fuse wire is to be used for geyser
When the main switch of the house circuit is put off, it disconnects the
A. Live wire
B. Neutral wire
C. Earth wire
D. None of the above
Find the incorrect statement
Which of the following describes the common domestic power supplied in India
A coil of copper wire is connected to a galvanometer. What would happen if a bar magnet is pushed into the coil with its north pole entering first
Permanent magnets are made of
Magnets are made from magnetic metals – iron, nickel and cobalt. These are the only pure metals that can be turned into a permanent magnet. Steel is an alloy of iron and so can also be made into a magnet. Alnico and Nipermag alloys are ferromagnetic, with a high coercivity (resistance to loss of magnetism) and are used to make permanent magnets.
By right – hand thumb rule for current carrying wire the thumb point toward the
Give names of two materials with which permanent magnets are made
The phenomena of electromagnetic induction is
Which one of the following is correct-
A. Fuse wire is an alloy of tin and lead
B. Switch is always connected to live wire
C. Alternate current is unidirectional
D. Higher is the value of current flow, weaker is the magnetic field
The magnetic field lines inside a long current-carrying solenoid are nearly-
When a coil carries current in an anti clockwise direction what pole does it create?
The device used for producing current is called
Magnetic field lines determine
What are the factors affecting the strength of magnetic field at a point due to a straight conductor carrying current?
Why does short circuit lead to the fuse wire burning?