Grade 9 Academic Science Unit 4 Electricity

Grade 9 Academic Science – Unit 4 Electricity Electricity Practice Test #1

1. What symbol is the unit of measurement for current? a. V b. A c. R d.  e. I

2. What is the potential difference across a toaster of resistance 27.4  when the current flowing through it is 4.375 A? a. 31.775 V b. 120 V c. 6.26 V d. 23.025 V

3. What is the rate of flow of electric charge? a. Resistance b. Power c. Voltage d. Current e. Energy

4. Human hands are naturally positively-charged. If there is a positive charge, why do we not have sparks flying from our skin on contact with other materials? a. Humans are sparkles, and as such, we do not emit sparkles. Rather, we absorb sparkles. b. The sparks that fly move into the human hands c. Our hands are moist, and the moisture creates a barrier-like layer between our hands and other materials that prevent sparks formation d. The sparks are invisible

5. What is “...an imbalance of electric charges on the surface of an object” called? a. Resistance b. Static Electricity c. Charging by Induction d. Conductor

6. In electricity, what is an insulator? a. Materials that impede the free flow of electrons b. Material that increases the free flow of electrons c. Material containing free-flowing electron d. The free flow of electrons through a material

7. What prevents the charge from flowing? a. Force b. Current c. Voltage d. Power e. Resistance 8. You charge charging a neutral object by bringing another charged object close to, but not touching, the neutral object. What is this charging process called? a. Charging by Contact b. Charging by Friction c. Charging by Induction d. Charging by Conduction

9. What does a VOLTMETER measure? a. The voltage difference between two points in an electric circuit b. The flow of volts in a circuit c. The resistance to voltage in a complete circuit d. The flow of electric current in a complete circuit

10. You have built a circuit with two lights. The lights burn very brightly, and when one of the light bulbs is removed, the other light continues to burn. What type of circuit do you have? a. Closed Circuit b. Series Circuit c. Parallel Circuit d. Practice Circuit

Use Ohm’s Law to solve the following problems. HINT: Remember, GRASP can be applied as a pathway to the answer.

11. A toaster connected to a 120 V power source has 12.0 A of current flowing through it. What is the resistance of the toaster?

12. How much current passes through a 25 Ω resistor that has a 100 V drop across the resistor?

13. In the diagram, two resistors are connected in a series

circuit with a battery. If R1 = 15 Ω, VT = 90 V and IT = 3

A, what is the resistance at R2? ANSWERS

Question Answer Question Answer

1 B 6 A

2 B 7 E

3 D 8 C

4 C 9 A

5 B 10 C

11 10 Ω

12 4 A

13 15 Ω