Advertisements
Advertisements
प्रश्न
(a) Observe the diagram given below and state whether the bulb will glow or not when we switch on K.
(b) Is it safe to handle the bulb when the switch is OFF?
(c) Give a reason for your answer in (b).
Advertisements
उत्तर
- In the given figure it is observed that the bulb is connected with Live wire and the key is connected with Neutral wire. When the key or switch is ON, the path of current flow is completed, hence the bulb will glow.
- It is NOT safe to handle the bulb when the switch is OFF as bulb is directly connected to live wire.
- In the OFF position, the bulb remains connected to the high potential terminal through the live wire, but no current flows through the bulb, as the return path is incomplete. In this condition, it is not safe to touch the bulb even from outside. As a result, if the switch is connected to the neutral wire, it might be deceiving and even harmful to the user.
APPEARS IN
संबंधित प्रश्न
State four most common electrical appliances based on heating effect of electric current. Why do we use finely heated platinum wire in surgery?
Why does the cord of an electric heater not glow while the heating element does?
An electric iron of 1100 W is operated for 2 hrs daily. What will be the electrical consumption expenses for that in the month of April? (The electric company charges Rs 5 per unit of energy).
Answer the following question:
what is the heating effect of the electric current? state any four applications of it?
Live wire and neutral wires have a 220 V potential difference.
Name any two appliances which work under the principle of heating effect of current.
Mark the correct choice
- Assertion: Electric appliances with a metallic body have three wire connections.
- Reason: Three-pin connections reduce the heating of the connecting wires.
Your teacher has shown you the following activity.
Activity: Teacher has wound a long insulated piece of wire around an iron nail in the form of a coil. Free ends of the wire are connected to a cell through a switch as shown in the following figure. The current is switched on and some pins are placed near the ends of the nail.
Write down any three questions that come to your mind about this activity.
Paheli took a wire of length 10 cm. Boojho took a wire of 5 cm of the same material and thickness. Both of them connected the wires as shown in the circuit given in the following figure. The current flowing in both the circuits is the same.
- Will the heat produced in both cases be equal? Explain.
- Will the heat produced be the same if the wires taken by them are of equal lengths but of different thickness? Explain.
If 220 V potential difference is applied across an electric bulb, a current of 0.45 A flows in the bulb. What must be the power of the bulb?
