Page 1: Probe and Ponder
Q1: If we don’t have an electric lamp, how can we find out if current is flowing in a circuit? Answer: We can use the Magnetic Effect. Place a magnetic compass near the wire. If current is flowing, the needle will deflect. Alternatively, if the current is high enough, we could feel the wire getting warm (Heating Effect), though this is less sensitive than a compass.
Q2: Is it possible to make temporary magnets? How? Answer: Yes. We can make temporary magnets called Electromagnets. This is done by winding an insulated wire around a magnetic material (like an iron nail) and passing electric current through it. It acts as a magnet only as long as the current flows.
Q3: How is heat generated in various electrical appliances? Answer: Heat is generated due to the resistance of the heating element (usually made of Nichrome) inside the appliance. When electric current fights against this resistance, electrical energy is converted into heat energy.
Q4: How do we know if a cell is dead? Can all cells be recharged? Answer:
- A cell is “dead” when the chemicals inside are used up and it can no longer produce a potential difference to move electrons. We know this when the appliance stops working.
- No, not all cells can be recharged. Standard dry cells (zinc-carbon or alkaline) are single-use. Only specific types, like Lithium-ion or Ni-MH batteries, are rechargeable.