2. A bulb circuit sits in the middle of a larger circuit containing a resistor, battery and switch. Closing and opening the switch will briefly induce a current in the bulb circuit. (a) What direction is the current in the bulb circuit, when you close the switch, CW or CCW? (b) What direction is the current in the bulb cireuit when you open the switch?
Solution
2. This will be governed by Lenz law for induced emf. The induction always tries to oppose the change by driving the opposite direction such that magnetic field change should be cancelled.
Hence, when switch is closed in outer circuit, current in outer circuit flows in clockwise CW , and to reduce the effect, the currect in secondary circuit containing bulb will be in opposite direction, i.e. counter clockwise CCW direction.
When switch is opened, currect tried to reduce in primary circuit, and hence magnetic field starts to drop. The secondary cuircuit trying to reduce the change in magnetic field will induce a current in the same directiomnof in primary circuit, i.e. CW direction.
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2- A bulb circuit sits in the middle of a larger circuit containing a.docx
1. 2. A bulb circuit sits in the middle of a larger circuit containing a resistor, battery and switch.
Closing and opening the switch will briefly induce a current in the bulb circuit. (a) What
direction is the current in the bulb circuit, when you close the switch, CW or CCW? (b) What
direction is the current in the bulb cireuit when you open the switch?
Solution
2. This will be governed by Lenz law for induced emf. The induction always tries to oppose the
change by driving the opposite direction such that magnetic field change should be cancelled.
Hence, when switch is closed in outer circuit, current in outer circuit flows in clockwise CW ,
and to reduce the effect, the currect in secondary circuit containing bulb will be in opposite
direction, i.e. counter clockwise CCW direction.
When switch is opened, currect tried to reduce in primary circuit, and hence magnetic field starts
to drop. The secondary cuircuit trying to reduce the change in magnetic field will induce a
current in the same directiomnof in primary circuit, i.e. CW direction.
