Ohms Law Practice Worksheet With Answers [PDF Download Available ... - Free Printable

Here's the complete solution to all 10 questions from the Ohm’s Law Worksheet, with clear explanations for each.

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Question 1: State Ohm’s law?

✔ Answer:
Ohm’s Law states that the current (I) flowing through a conductor between two points is directly proportional to the voltage (V) across the two points and inversely proportional to the resistance (R) between them.

Mathematically:
V = I × R
or
I = V / R
or
R = V / I

This holds true for ohmic materials (like most metals) at constant temperature.

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Question 2: A 5 V source connects to a 10 ohms resistor. What is current?

✔ Answer:
Use Ohm’s Law: I = V / R

Given:
V = 5 V
R = 10 Ω

I = 5 / 10 = 0.5 A

➡️ Current = 0.5 Amperes

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Question 3: A 2.2 kohm resistor has 15 mA current passing through it. Find the value of connected voltage source.

✔ Answer:
Use Ohm’s Law: V = I × R

First, convert units:

- R = 2.2 kΩ = 2200 Ω
- I = 15 mA = 0.015 A

V = 0.015 × 2200 = 33 V

➡️ Voltage source = 33 Volts

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Question 4: A circuit contains 12-volt battery connected to a light bulb having resistance of 5 ohms. Find the current.

✔ Answer:
Use Ohm’s Law: I = V / R

V = 12 V
R = 5 Ω

I = 12 / 5 = 2.4 A

➡️ Current = 2.4 Amperes

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Question 5: Two batteries, one of 3 V and other one of 12 V are connected in series to a resistor of 1 kohm. Find the current that will flow through the resistors.

✔ Answer:
When batteries are connected in series, their voltages add up (if they are aiding each other — assumed here unless stated otherwise).

Total voltage: V_total = 3 V + 12 V = 15 V

Resistance: R = 1 kΩ = 1000 Ω

I = V / R = 15 / 1000 = 0.015 A or 15 mA

➡️ Current = 15 milliamperes

*(Note: If batteries were opposing, we’d subtract — but question doesn’t say so, so we assume aiding.)*

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Question 6: Two lamps, each having resistance of 3 ohms connect in series. What current will flow if a voltage source of 5 V is connected at input.

✔ Answer:
In series, total resistance adds up:

R_total = 3 Ω + 3 Ω = 6 Ω

V = 5 V

I = V / R = 5 / 6 ≈ 0.833 A

➡️ Current ≈ 0.833 Amperes

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Question 7: How current changes in circuit for constant voltage, when resistance value increases?

✔ Answer:
From Ohm’s Law: I = V / R

If voltage (V) is constant and resistance (R) increases, then current (I) decreases.

➡️ Current decreases as resistance increases (inverse relationship).

Example: If R doubles, I halves (for same V).

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Question 8: Certain resistance has 10 Amps current through it, when a 50 V source is applied. Find the value of resistance.

✔ Answer:
Use Ohm’s Law: R = V / I

V = 50 V
I = 10 A

R = 50 / 10 = 5 Ω

➡️ Resistance = 5 ohms

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Question 9: A 5 V, 3 mA led connected to a 12 V source requires a series resistor of how many ohms?

✔ Answer:
The LED requires 5 V and draws 3 mA. The source is 12 V, so the extra voltage must be dropped across a series resistor.

Voltage drop across resistor:
V_R = V_source - V_LED = 12 V - 5 V = 7 V

Current through resistor = current through LED = 3 mA = 0.003 A

Now use Ohm’s Law: R = V / I

R = 7 / 0.003 ≈ 2333.33 Ω

➡️ Series resistor ≈ 2333 ohms (or 2.33 kΩ)

*(In practice, you might choose a standard resistor like 2.2kΩ or 2.4kΩ depending on tolerance and desired brightness.)*

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Question 10: Find current supplied by 10 V source to two parallel resistors of 6 ohms?

✔ Answer:
Two 6 Ω resistors in parallel.

Equivalent resistance (R_eq) for two equal resistors in parallel:
R_eq = R / 2 = 6 / 2 = 3 Ω

Alternatively, using formula:
1/R_eq = 1/6 + 1/6 = 2/6 = 1/3 → R_eq = 3 Ω

Now, current from source: I = V / R_eq = 10 / 3 ≈ 3.333 A

➡️ Total current supplied = 3.333 Amperes

*(Each resistor gets half: 1.666 A each, since they’re equal.)*

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✔ Summary of All Answers:

1. Ohm’s Law: V = I × R
2. 0.5 A
3. 33 V
4. 2.4 A
5. 15 mA
6. 0.833 A
7. Current decreases
8. 5 Ω
9. ~2333 Ω
10. ~3.333 A

Let me know if you want diagrams or further clarification on any problem!