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Question : 32
Total: 39
(A) (i) Why is an alternating current (A.C.) considered to be advantageous over direct current (D.C.) for the long distance transmission of electric power?
(ii) How is the type of current used in household supply different from the one given by a battery of dry cells?
(iii) How does an electric fuse prevent the electric circuit and the appliances from a possible damage due to short circuiting or overloading.
OR
(B) For the current carrying solenoid as shown, draw magnetic field lines and give reason to explain that out of the three points A, B and C, at which point the field strength is maximum and at which point it is minimum?
(ii) How is the type of current used in household supply different from the one given by a battery of dry cells?
(iii) How does an electric fuse prevent the electric circuit and the appliances from a possible damage due to short circuiting or overloading.
OR
(B) For the current carrying solenoid as shown, draw magnetic field lines and give reason to explain that out of the three points A, B and C, at which point the field strength is maximum and at which point it is minimum?
Solution:
(A) (i) Alternating current can be transmitted to long distances without much loss of electric energy. Hence, it is advantageous over direct current for long-range transmission of electric energy.
(ii) A dry cell (or battery of any type) supplies Direct Current or DC. Household outlets supply Alternating Current or AC.
(iii) A common application of Joule's heating is the fuse used in electric circuits. It protects circuits and appliances by stopping the flow of any unduly high electric current. The fuse is placed in series with the device. It consists of a piece of wire made of a metal or an alloy of appropriate melting point, for example aluminium, copper, iron, lead etc. If a current higher than the specified value flows through the circuit, the temperature of the fuse wire increases. This melts the fuse wire and breaks the circuit. The fuse wire is usually encased in a cartridge of porcelain or similar material with metal ends.
OR
(B) (ii)
Minimum - at point B; Maximum - at pointA
(ii) A dry cell (or battery of any type) supplies Direct Current or DC. Household outlets supply Alternating Current or AC.
(iii) A common application of Joule's heating is the fuse used in electric circuits. It protects circuits and appliances by stopping the flow of any unduly high electric current. The fuse is placed in series with the device. It consists of a piece of wire made of a metal or an alloy of appropriate melting point, for example aluminium, copper, iron, lead etc. If a current higher than the specified value flows through the circuit, the temperature of the fuse wire increases. This melts the fuse wire and breaks the circuit. The fuse wire is usually encased in a cartridge of porcelain or similar material with metal ends.
OR
(B) (ii)
(ii) Outside the solenoid magnetic field is minimum. At the ends of solenoid, magnetic field strength is half to that inside it. So field strength is:
Minimum - at point B; Maximum - at point
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