Advertisements
Advertisements
प्रश्न
Find the odd one out and give its explanation.
विकल्प
Tungsten
Nichrome
Aluminium
Iron
Advertisements
उत्तर
Nichrome
Explanation-
Nichrome is an alloy used for making wires, while others are soft metals.
APPEARS IN
संबंधित प्रश्न
An electric iron of resistance 20 Ω takes a current of 5 A. Calculate the heat developed in 30 s.
An electric heater of resistance 8 Ω draws 15 A from the service mains 2 hours. Calculate the rate at which heat is developed in the heater.
Name any two effects of electric current.
The safety device based on the heating effect of electric current is called a ______.
Write Joule's law of heating.
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?
Explain why, the current that makes the heater element very hot, only slightly warms the connecting wires leading to the heater.
How much heat will an instrument of 12 W produce in one minute if it is connected to the heat produced by it?
If the current flowing through a fixed resistor is halved, the heat produced in it will become:
Three heaters each rated 250 W, 100 V are connected in parallel to a 100 V supply. Calculate:
- the total current taken from the supply
- the resistance of each heater and
- the energy supplied in kWh to the three heaters in 5 hours.
Give Scientific reasons.
In the electric equipment producing heat e.g. iron, electric heater, boiler, toaster etc, an alloy such as Nichrome is used, not pure metals.
Give Scientific reason.
In practice, the unit kWh is used for the measurement of electrical energy, rather than joule.
Solve the following example.
Two tungsten bulbs of wattage 100 W and 60 W power work on 220 V potential difference. If they are connected in parallel, how much current will flow in the main conductor?
Name the factors on which the heat produced in a wire depends when current is passed in it, and state how does it depend on the factors stated by you.
In an electric bulb, coil of _______ metal is used.
The electricity bill specifies the usage in _______.
Which of the following substance contracts on heating?
Write scientific reason.
A coil made up of alloy Nichrome is used in the electric heater cooker as a resistor.
How can overloading be avoided?
Explain the heating effect of electric current.
Heating effect of current is called ______
The heating element of an electric iron is made up of:
Assertion: Bending of wire decreases the resistance of the electric wire.
Reason: The resistance of a conductor depends on length, thickness, nature of material and temperature of the conductor.
How does use of a fuse wire protect electrical appliances?
Why is parallel arrangement used in domestic wiring?
(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).
Can we use the same fuse in a geyser and a television set? Explain.
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.
Name the effect of the current responsible for the glow of the bulb in an electrical circuit.
A trip switch is a ______ safety device.
Explain why fuse wire is always connected in a series arrangement.
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?
What is the heating effect of electric current?
When a current I flows through a wire of resistance R for time t then the electrical energy produced is given by ______.
