BMST - Basic Math and Science Electrical Circuits and Ohm's Law Questions and Answers 2 — Questions and Answers
Question 1: According to Ohm's Law, if voltage is 12V and resistance is 4Ω, what is the current?
- 3A (Correct answer)
- 48A
- 8A
- 0.33A
Correct answer: 3A
Ohm's Law: I = V/R = 12/4 = 3 amperes.
Ohm's Law states V = IR, where V is voltage (volts), I is current (amperes), and R is resistance (ohms). Rearranging to solve for current: I = V/R = 12V / 4Ω = 3A. This means 3 amperes of current flow through the circuit. Ohm's Law is the fundamental relationship in electrical circuits.
Question 2: In a series circuit with three resistors of 2Ω, 3Ω, and 5Ω, what is the total resistance?
- 10Ω (Correct answer)
- 0.97Ω
- 3.33Ω
- 30Ω
Correct answer: 10Ω
In series circuits, total resistance is the sum: 2 + 3 + 5 = 10Ω.
In a series circuit, current flows through each resistor sequentially, and the total resistance equals the sum of individual resistances: R_total = R₁ + R₂ + R₃ = 2Ω + 3Ω + 5Ω = 10Ω. This is because each resistor adds to the opposition of current flow. The current is the same through each resistor, but voltage divides among them.
Question 3: What is the unit of electrical resistance?
- Ohm (Ω) (Correct answer)
- Ampere (A)
- Volt (V)
- Watt (W)
Correct answer: Ohm (Ω)
Resistance is measured in ohms (Ω), named after Georg Simon Ohm.
The ohm (symbol: Ω) is the SI unit of electrical resistance, named after German physicist Georg Simon Ohm. One ohm is defined as the resistance between two points when one volt produces one ampere of current: 1Ω = 1V/1A. Amperes measure current, volts measure voltage (potential difference), and watts measure power.
Question 4: What happens to current in a circuit if resistance doubles while voltage stays constant?
- Current is halved (Correct answer)
- Current doubles
- Current stays the same
- Current quadruples
Correct answer: Current is halved
From I = V/R, doubling R halves I when V is constant.
According to Ohm's Law (I = V/R), current is inversely proportional to resistance when voltage is constant. If R doubles (R becomes 2R), then I = V/(2R) = (1/2)(V/R), so current is halved. This inverse relationship means that increasing resistance reduces current flow, which is why resistors are used to control current in circuits.
Question 5: In a parallel circuit, what is true about the voltage across each branch?
- It is the same across all branches (Correct answer)
- It is different for each branch
- It increases with each branch
- It equals zero
Correct answer: It is the same across all branches
In parallel circuits, all branches share the same voltage from the source.
In a parallel circuit, each branch connects directly between the same two nodes (connection points). Therefore, the voltage across each parallel branch is identical and equal to the source voltage. However, the current divides among branches, with more current flowing through branches with lower resistance. This is a key distinction from series circuits, where voltage divides but current is the same.
Question 6: What is electrical power measured in?
- Watts (Correct answer)
- Ohms
- Amperes
- Joules
Correct answer: Watts
Power is measured in watts (W). P = V × I.
Electrical power is measured in watts (W) and can be calculated as P = VI (voltage × current), P = I²R, or P = V²/R. One watt equals one joule per second, representing the rate at which electrical energy is converted to other forms (heat, light, motion). Joules measure energy (not power), amperes measure current, and ohms measure resistance.
BMST - Basic Math and Science Electrical Circuits and Ohm's Law Questions and Answers 2
According to Ohm's Law, if voltage is 12V and resistance is 4Ω, what is the current?