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प्रश्न
State four most common electrical appliances based on heating effect of electric current. Why do we use finely heated platinum wire in surgery?
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उत्तर
The four most common appliances based on the heating effect of electrical current are electric iron, electric heater, electric oven and electric toaster. Finely heated platinum wire is used in surgery for cutting tissues much more efficiently than a knife.
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संबंधित प्रश्न
How does the resistance of a wire vary with its area of cross-section?
The safety device based on the heating effect of electric current is called a ______.
How does the resistance of a wire vary with its:
diameter?
Why does the connecting cord of an electric heater not glow hot while the heating element does?
The elements of electrical heating devices are usually made of:
(a) tungsten
(b) bronze
(c) nichrome
(d) argon
The heat produced in a wire of resistance 'x' when a current 'y' flows through it in time 'z' is given by:
(a) x2 × y × z
(b) x × z × y2
(c) y × z2 × x
(d) y × z × x
How does the wire in the filament of a light bulb behave differently to the other wires in the circuit when the current flows?
What property of the filament wire accounts for this difference?
Give Scientific reason.
In practice, the unit kWh is used for the measurement of electrical energy, rather than joule.
Identify the figure and give its use.
Identify the figure and give its use.
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).
The ‘live’ and the ‘neutral’ wires have potential difference of _______.
Which metal is used to make the filament of an electric bulb?
What is a short circuit?
What is overloading?
What is used to turn off the sudden increase in current in the electrical circuit of the house nowadays?
Live wire and neutral wires have a 220 V potential difference.
Explain the application of heating effect of electric current in an electric bulb with a diagram.
True or False – If False give the correct answer
The fuse wire does not melts whenever there is overload in the wiring.
Define fuse.
A fuse wire repeatedly gets burnt when used with a good heater. It is advised to use a fuse wire of:
The heating element of an electric iron is made up of:
B1, B2 and B3 are three identical bulbs connected as shown in Figure. When all the three bulbs glow, a current of 3A is recorded by the ammeter A.
- What happens to the glow of the other two bulbs when the bulb B1 gets fused?
- What happens to the reading of A1, A2, A3 and A when the bulb B2 gets fused?
- How much power is dissipated in the circuit when all the three bulbs glow together?
Three incandescent bulbs of 100 W each are connected in series in an electric circuit. In another circuit another set of three bulbs of the same wattage are connected in parallel to the same source.
- Will the bulb in the two circuits glow with the same brightness? Justify your answer.
- Now let one bulb in both the circuits get fused. Will the rest of the bulbs continue to glow in each circuit? Give reason.
Name two electric devices for each where
- heating effect of current is used and
- magnetic effect of current is used.
An electric fuse has a body made of ceramic and two points for connecting the fuse wire.
Name a few appliances which work on the basis of the heating effect of current.
The following is not a safety device.
A fuse is used in an electric circuit to stop high currents flowing through the circuit.
Explain why fuse wire is always connected in a series arrangement.
Find the odd one out.
Two students decided to investigate the effect of water and air on iron object under identical experimental conditions. They measured the mass of each object before placing it partially immersed in 10 ml of water. After a few days, the object were removed, dried and their masses were measured. The table shows their results.
| Student | Object | Mass of Object before Rusting in g |
Mass of the coated object in g |
| A | Nail | 3.0 | 3.15 |
| B | Thin plate | 6.0 | 6.33 |
What might be the reason for the varied observations of the two students?
Write an expression for the amount of heat produced in a resistor when an electric current is passed through it stating the meanings of the symbols used.
Anannya responded to the question: Why do electrical appliances with metallic bodies are connected to the mains through a three-pin plug, whereas an electric bulb can be connected with a two-pin plug?
She wrote: Three-pin connections reduce heating of connecting wires.
- Is her answer correct or incorrect? Justify.
- What is the function of a fuse in a domestic circuit?
