Question

in the givenfig why will the blub x brightness increase if switch s is closed ​

Answer 1

See what happens after the switch is closed:

• Current flows from the postive terminal to the negative terminal(since it's opposite to the flow of electrons).
• Current goes towards bulb x and then distributes equally among bulb y and z.
• Current continues to flow in the same directed path till the switch is again opened.

Now herein, since bulb x gains the exact current flowing in the whole circuit, say ß Ampere, because it is connected in series with the circuit. The other two bulbs gain a comparitively lesser current due to its equal distribution among the two bulbs (since they are in a parallel combination).

Thus, bulb x glows brighter than the other two bulbs.