ASSET PRACTICE

A regular telephone neither uses batteries, nor is it connected to the electric supply. From where does it get the energy (electricity) required for its working?

• It does not require any energy for its working.

• It gets energy through the regular telephone wires.

• It gets energy every time someone speaks into it.

• It gets energy every time someone dials a number.

Srihari has a torch with him and 2 new batteries. However, the torch requires 3 batteries to work. Is there any way Srihari can get the torch to glow?

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In the working of which of these is air resistance desirable and important?

• superfast trains

• parachutes

• pendulums

• fighter aeroplanes

Here is the picture of an aircraft, with the forces working on it shown.

Identify the force that corresponds to the question mark.

• Buoyancy

• Atmospheric pressure

• Gravity

• Density

While repairing a fan, a trainee electrician connects the wires wrongly. When the fan is switched on, it rotates at the proper speed, but in the OPPOSITE direction. What will happen as a result of this?

• The fan will work for sometime and then stop.

• The fan will consume more power.

• The fan will not throw down any air.

• The fan will work perfectly.

Electrical fires cannot be safely put out by dousing them with water. However, fire extinguishers that spray carbon dioxide on the fire work very effectively because it forms a blanket around the burning material.

But these carbon dioxide extinguishers cannot be used for wood fires. Why?

• The carbon dioxide blanket itself acts as a fuel and starts burning along with the wood.

• The extinguished wood can retain enough heat inside the carbon dioxide blanket to re-ignite when the gas dissipates.

• In the presence of carbon dioxide from the extinguisher, the burning wood reacts with oxygen to release heat and make the fire worse.

• Carbon dioxide reacts with wood to give carbon and oxygen; the oxygen makes the fire worse and the carbon burns along with the wood.

In which of these cases is there no ROTATIONAL MOTION?

• operating a pulley

• hitting a shuttlecock

• riding a bicycle

• using a beam balance

During a power cut, lights, fans, televisions and other electrical devices stop functioning, but most telephones continue to work. Why is that?

• Telephones do not use electricity.

• All telephones have cells (batteries) inside which provide them power.

• Telephones receive electric supply through the wires connecting them to the exchange.

• Telephones store the electricity when there is no power cut and use them during power cuts.

Sonika is working with the circuit shown in the figure. The circuit has two gaps - X and Y. She has wires of five different materials - I, II, III, IV and V. She knows that the bulb will light up only when both gaps are filled with conducting materials.

She records her observations in a table. After completing the experiment, ink fell on the paper and she lost entries in row 3. Based on the rest of the information in the table, what could be the materials in row 3?

• I and III

• II and III

• III and IV

• IV and V

In the solar panel shown here, one form of energy is converted into another. An example of a device in which the energy conversion is OPPOSITE to that of the solar panel is_____________.

• a candle

• a radio

• a tube light

• a steam engine