Physics Past Questions and Answers

In storing magnets, keepers are used to

A Reduced self-demagnetization
B Cancel the effect of the earth's magnetic field
C Protect the magnet from stray electric field
D Increase the strangth of the magnets

Question 1747:

A 10\(\mu\)C charge moves with a velocity of 1.0 x 10⁵ ms^-1 at right angle to a uniform magnetic field of flux density 5.0 x 10^-4T. Calculate the force on the charge

A 5.0 x 10^-5N
B 5.0 x 10^-4N
C 5.0 x 10⁵N
D 5.0 x 10⁶N

Question 1748:

Which of the following statements is not correct about steel and soft iron?

A Steel is more magnetized than soft iron
B Permanent magnets are usually made of steel
C Soft iron is more readily magnetized than steel
D Soft iron more readily loses its magnetism than steel

Question 1749:

What determines the polarity at the ends of an electromagnet? The

A Magnitude of the current passing through the wire
B Material of the core of the magnet
C Material of the coil
D Direction of current in the wire

Question 1750:

How many beta particle(s) are emitted in the radioactive decay of \(^{198}_{79}Au \leftarrow ^{198}_{80}Hg\)?