153279
If a current carrying circular loop is placed in $a x-y$ plane as shown in adjoining figure and a magnetic field is applied along $z$-axis, then the loop will
1 Contract
2 Expand
3 Move towards- $\mathrm{x}$-axis
4 Move towards $+\mathrm{x}$-axis
Explanation:
B If a current carrying circular loop is placed in $\mathrm{x}-\mathrm{y}$ plane then every portion of the current carrying circular loop experiences radially outward force, hence the loop expands.
JCECE-2013
Moving Charges & Magnetism
153329
Cathode rays are passed between the poles of a magnet as shown in figure. The effect of magnetic field is
1 to increase velocity of rays
2 to deflect the rays towards S-pole
3 to deflect the rays towards N-pole
4 to deflect the rays perpendicular to the plane of paper, upwards
Explanation:
D The magnetic lens of force emerge from North pole and enter south pole. Cathode rays are fast moving electrons and direction of current is taken opposite to direction of motion of electrons. According to the question set up magnetic field is from north pole to south pole, direction of current is opposite to direction of cathode rays, so from Fleming's left hand rule, force acts perpendicular to plane of paper upwards.
153279
If a current carrying circular loop is placed in $a x-y$ plane as shown in adjoining figure and a magnetic field is applied along $z$-axis, then the loop will
1 Contract
2 Expand
3 Move towards- $\mathrm{x}$-axis
4 Move towards $+\mathrm{x}$-axis
Explanation:
B If a current carrying circular loop is placed in $\mathrm{x}-\mathrm{y}$ plane then every portion of the current carrying circular loop experiences radially outward force, hence the loop expands.
JCECE-2013
Moving Charges & Magnetism
153329
Cathode rays are passed between the poles of a magnet as shown in figure. The effect of magnetic field is
1 to increase velocity of rays
2 to deflect the rays towards S-pole
3 to deflect the rays towards N-pole
4 to deflect the rays perpendicular to the plane of paper, upwards
Explanation:
D The magnetic lens of force emerge from North pole and enter south pole. Cathode rays are fast moving electrons and direction of current is taken opposite to direction of motion of electrons. According to the question set up magnetic field is from north pole to south pole, direction of current is opposite to direction of cathode rays, so from Fleming's left hand rule, force acts perpendicular to plane of paper upwards.
