Ans. The deflection in magnetic needle shows that the circuit is complete and the solution conducts electricity.
Ans. Chromium is usually electroplated on car parts such as bumpers and bicycle handlebars made of steel.
Ans. Tin is electroplated on iron for making cans because tin is less reactive than iron. Thus, food does not come into contact with iron and is protected from getting spoilt.
Ans. Though a material may conduct electricity, it may not conduct it as easily as a metal. As a result, the circuit of the tester may be complete and yet the current through it may be too weak to make the bulb glow.
Ans. A brand new bicycle has shiny handlebar and wheel rims. However, if these are accidentally scratched, the shiny coating comes off revealing a not so shiny surface beneath.
Ans. It is dangerous to touch a working electrical appliance with wet hands because the tap water is a good conductor of electricity due to which it may conduct electric current and gives us an electric shock.
Ans. Two common application of the chemical effect of electric current are:
i. Electroplating of metals
ii. Purification of metals
Ans. In the process of electroplating, the metal to be electroplated is taken as cathode (negative) and the one used for coating is chosen as the anode (positive). Thus, negative terminal will be connected to the iron object.
Ans. Water is a conductor of electricity, so if the electricity supply is not cut off and firemen come in contact with wet electric switches, electric wires and other electrical appliances, they may get electrocuted.
Ans. Due to the heating effect of current, the filament of the bulb gets heated to a high temperature and it starts glowing. However, if the current through a circuit is too weak, the filament does not get heated sufficiently and it does not glow.
Ans. The passage of an electric current through a conducting liquid causes chemical reactions. The resulting effects are called chemical effects of currents. Example – Deposit of metal formed when electric current is passed through copper sulphate solution (during electroplating).
Ans. The properties of chromium metal that make it suitable for electroplating are:
i. It has a shiny appearance.
ii. It does not corrode.
iii. It resists scratches.
Image from NCERT
Ans. Tap water, vinegar and lemon juice are conductors of electricity. Most liquids that conduct electricity are solutions of acids, bases and salts.
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