Question

Please answer..

Overview:

When a wire is attached to the positive terminal of a power source, such as a battery, and to the negative terminal of the battery a potential difference is set across that wire and a current is generated through that wire. Depending on how much resistance there is in the wire will affect the amount of current through that wire. Adding more resistance will further affect the amount of current.  In this experiment you will measure both the current through different resistive elements (such as light bulbs and resistors) and the voltages across these elements.

Light Bulbs

Start the investigation of the amount of current which flows through a circuit element (such as a light bulb, or a resistor) by placing 2 D-Cell batteries into the battery holder on the circuit board.  Screw in a round light bulb into the receptacle marked “LAMP 1”.  Connect wires that have alligator clips attached to both ends from the positive terminal (located near the battery holder) to one of the connectors of the single-pole single-throw (SPST) switch (SW3) marked with the number 22.  Connect another wire from the other connector to this switch (23) to one of the connectors on one side of LAMP 1.  Connect a third wire from the other side of LAMP 1 to the ground terminal located near the bottom edge of the circuit board (35).  By pressing down on the red button of SW3 you close the circuit and allow the light bulb to glow.

Question 1:  (discussion) Does the round light bulb glow brightly, or dimly?

Change the round light bulb for a long light bulb and close the circuit by pressing the switch.

Question 2: (discussion) Does this light bulb glow brighter, or dimmer, compared to the round light bulb?

Add another long light bulb into the socket marked LAMP 2.  Detach the end of the wire that is connected to the negative terminal (35) and attach it to one side of LAMP 2.  Take another wire and connect the other side of LAMP 2 to the negative terminal. By doing this you have connected a second light bulb “in series” with the first light bulb.  Now, press the red button on SW3 to close the circuit.

Question 3: (discussion) How does the brightness of each of these two bulbs compare to each other (one is brighter than the other; they are of the same brightness).  How does the brightness of these two light bulbs compare to the brightness of having just one long light bulb in the circuit?

Answer 1

Considering resistance of round light bulb to be greater than long light bulb. Since brightness depends on current passing through it when potential difference is constant. So current in the round bulb will less since it's resistance is more so brightness in round bulb will be less than that of long light bulb.

Now when two light bulbs are connected in series it means total current in the circuit will decrease in comparison to when only one bulb was there. Now as current is decreased and individual resistance is same as before so brightness will decrease.