Magnetic effects of current

An Electric charge in a uniform motion produces

• An Electric Field only

• An Magnetic field only

• Both Electric Field & Magnetic field

• Neither of them

Two parallel wires carry current in the same direction attract each other because of

• Potential difference between them

• Mutual inductance between them

• Electric forces between them

• Magnetic forces between them

The strength of the magnetic field around a straight conductor carrying an electric current

• is same every where around the conductor

• obeys inverse square law

• is directly proportional to the square root of the distance

• None of the above

A wire is parallel to the lines of the force of the magnetic field and the current flows in the wire. Then

• The wire will experience a force along the direction of the magnetic field

• The wire will not experience any force

• The wire will experience the torque

• The wire will experience a perpendicular force

A length of the wire carries a steady current. It is bent first to form a circular plane coil of one turn .The same length is now bent more sharply to give a double loop of the smaller radius .The magnetic field at the center caused by the same current is

• A quarter of its first value

• Un altered

• Four times its first value

• A half of its first value

Through two parallel wires A & B , 10 and 2 ampere of the currents are passed respectively in opposite direction. If the wire A is infinitely long and the length of the wire B is 2m. the force on the conductor B which is situated at 10 cm distance from A will be

• 8×10^-6 N

• 8×10^-5 N

• 4×10^-5 N

• 4×10^-5 N

An electron having a charge e moves with a velocity v in the x -direction. An electric field acts on it in y- direction. The force on the electron acts in

• Positive direction of the y - axis

• Negative direction of the y - axis

• Positive direction of the x – axis

• Negative direction of the x - axis

The resulting magnetic field at the point O due to the current carrying wire shown in the figure

• Points vertically upwards

• Points vertically downwards

• is zero

• Can not be determined

A semicircular wire of radius r , carrying a current I, is placed in a magnetic field of the magnitude B .The force acting on it

• can never be zero

• can have the maximum magnitude 2BIr

• can have the maximum magnitude BIπr

• can have the maximum magnitude Bir

A experimenter investigates the variation of the force F between the long , parallel current carrying conductors a distance d apart .A straight –line graph should be obtained on plotting

• F against d

• F against $\frac{1}{d}$

• F against $\frac{1}{d^2}$

• log |F| against d