(a) An electric bulb is rated as 50 W, 220 V, calculate the energy consumed by the bulbs in 20 minutes. Express your answer in commercial units of electric energy.
(b) What is the difference in construction of a DC generator than that of an AC generator.
(c) Explain the woking of commutator in DC generator.
Answers
Answer:
Answer to your question are given below:-
Explanation:
(a).
Now you have asked the energy consumed by the electric bulb that has 50W power rating and 220 V and is used for around 20 minutes.
Now if you want to calculate the energy consumption, then it is certain that you have to multiply the Watt of power consumed by the total number of hours this power has been used.
So here the time of usage is 20 minutes which is equal to 0.33 hours.
Now we have 50 Watts of power is used in 0.33 hours
So the energy consumed is 50 W X 0.33 Hrs = 16.5 Watts hrs = 16.5 Joules of energy is consumed.
(b).
Difference in construction of DC generator and AC generator
You have to keep in mind that AC and DC generators are very different in construction. In AC generator, the current flowing through the circuit reverses or changes direction in a periodic manner. The DC generator is one in which the direction of flow of current does not change. It is maintained in the same direction, throughout the cycle.
The next big difference between the two is that the AC generator makes use of a coil that remains fixed while the magnet that surrounds it rotates. While the DC generator uses a type of coil that is not fixed, but rotates while the magnetic field is fixed.
In an AC generator, the commutators are not used while in the DC generator the commutators are used so the current flow can be regulated in one direction only.
The AC generator is provided with the Slip rings while the one that is DC generator type is provided with the Split rings.
In AC generator, the slip rings and commutators do not easily wear out but in the DC type of generator, the slip rings will have to be replaced very often as they wear out easily. This that to construct a AC generator cost is less while that of a DC generator the cost s more.
(c)
The working of a commutator in a DC generator
When speaking of the commmutator in a DC generator, this acts as a special type of reversing switch. It is used for altering the direction of the current flow in the circuit. So the emf that is induced in the coil in DC generator, is alternating type. This means that the current that flows through the armature coil is also alternating type.
The commutator is used for reversing the direction of the current at a fixed intervals. This happens the moment the coil exceeds the neutral axis of the magnet. So this is what proves helpful in producing the unidirectional type of current or Direct current.