Science Lab

[ImagineDragons]

Would someone mind checking my answers on a short science lab?

Here it is:

In a series circuit, electrons travel along a single pathway. The movement of the
electrons through the circuit produces current. In a simple circuit, a battery can be
used as a source of electrons. Current increases as the voltage of the battery
increases. A 12-volt battery, for example, can push more electrons through a circuit
than a 9-volt battery.
The table below shows the effect that increasing voltage has on the brightness of a
light bulb.

Voltage (V) Light Bulb
1 No Light
4 Dim Light
12 Bright Light

Light bulbs and motors are called loads. Loads are sources of resistance. In a series
circuit, each electron must flow through consecutive resistors. If there are multiple
light bulbs connected in series, a single charge flowing through the circuit must
pass through all of the light bulbs. As the overall resistance in the circuit increases,
each light bulb shines a littler dimmer. This effect occurs because as the resistance
increases, the rate at which each electron flows through the circuit is reduced. It is
important to remember that as resistance increases, current decreases.
The table below shows how adding more resistance affects the current in a series
circuit that is supplied by a 10-volt battery.

Number Of Lightbulbs Total Resistance (Ω) Current (amps)
1 14.9 0.67
2 30.3 0.33
3 45.5 0.22
4 58.8 0.17


Use the tables to answer the following questions:
1. How does changing the voltage in a circuit affect the current in the circuit?

My answer:

I need help understanding this one

2. What is the impact of adding more light bulbs in series?

My Answer:
As you add more bulbs, the total resistance (Ω) increases and the Current (amps) decreases.

3. In the series circuit, is the current constant throughout the circuit, or does it
vary?

My answer:

The current is not constant throughout the circuit, it varies.

[Canary42]

It's over 60 years since I covered this at school, but I believe your third answer is incorrect - the current is constant if my memory is correct. (If this weren't the case, Xmas tree lights which are connected in series would not all glow at the same brightness)

Your second answer is correct, although you might add the bit about the bulbs being dimmer.

For your first answer, you possibly need to address the fact that the increased voltage pushes more electrons through the circuit, which [work it out, it's in the explanation in your question]

I hope this helps rather than hinders your understanding.

[ImagineDragons]

Do you think either chart shows the first or third answer?

[Canary42]

Oooops, I've been giving this some more thought and I now believe your third answer is in fact correct - my Xmas lights example is based on Alternating Current supply which is a whole different case, not Direct Current which you get from a battery.

Perhaps you better wait for a more qualified responder, sorry.

P.S. I don't understand your reference to a chart.

[ImagineDragons]

The tables not chart sorry my bad

[Buenchico]

1. Ohms law states Voltage = Current x Resistance. Therefore if the resistance remains constant (as it does in a simple circuit where you keep the same number of bulbs), voltage and current are directly proportional. (i.e. if you double the voltage you double the current).

2. For a constant voltage, the current and resistance are inversely proportional. Therefore, as you've correctly asserted, increasing the resistance (through adding more bulbs) decreases the current.

3. The current throughout a series circuit is determined by the potential difference (voltage) across the circuit and the resistance within it. i.e it's constant.

[Old_Geezer]

I agree with chico, but point out that you are told to use the tables so probably need to expand your answers with examples and comparisons from them.

[Old_Geezer]

PS were the current variable how would you explain the electron jam where the current dropped and all the electrons came crashing into each other at some point ?