test prep
multiple choice
circle the letter of the best answer.
cost of using household appliances
bar graph with appliance 1, 2, 3 and cost per hour (¢/h) axis
1. which of the following is a valid interpretation of the graph?
a the voltage is highest in appliance 1.
b appliance 1 uses the most power.
c during one month, a family pays more to run appliance 1 than appliance 2.
d appliance 1 draws the least current.
2. your alarm clock has a voltage of 120 v and a resistance of 1200 ω. what current does the alarm clock draw?
a 0.10 a
b 10.0 a
c 12.0 a
d 100 a
3. you want to build a device that can conduct current but will be safe if touched by a person. which of the following pairs of materials could you use?
a glass to conduct and rubber to insulate
b copper to conduct and silver to insulate
c sand to conduct and plastic to insulate
d silver to conduct and plastic to insulate
4. how does a fuse prevent electrical fire?
a by providing a path for excess charges to get to the ground
b by melting if the current gets too high
c by reducing the voltage supplied to electrical devices
d by storing potential energy for later use
5. what happens when an object is rubbed against another object to charge by friction?
a electrons are transferred from one object to another.
b electrons in one of the objects disappear.
c electrons in one object suddenly become negatively charged.
d electrons are created by the friction between the objects.
constructed response
use your knowledge of science to help you answer question 6. write your answer on a separate sheet of paper.
image of old cell phone and device
6. a lightning bolt can have a voltage of over 100 million volts. explain why lightning cannot power your cell phone but a 6 - volt battery can. then explain what would happen if a 100 - million - volt battery was plugged into a cell phone. use ohm’s law in your answer.

Question

Accepted Answer

### Question 2
# Explanation:
## Step1: Recall Ohm's Law
Ohm's Law is given by $ I = \frac{V}{R} $, where $ I $ is current, $ V $ is voltage, and $ R $ is resistance.
## Step2: Substitute Values
Given $ V = 120 \, \text{V} $ and $ R = 1200 \, \Omega $, substitute into the formula: $ I = \frac{120}{1200} $.
## Step3: Calculate Current
Simplify $ \frac{120}{1200} = 0.10 \, \text{A} $.
# Answer:
A. 0.10 A

### Question 1
# Brief Explanations:
- Option A: The graph shows cost per hour, not voltage. Eliminate A.
- Option B: Power $ P = \text{Cost per hour} \times \text{Rate (assumed constant) or related to cost. Higher cost per hour (Appliance 1) implies more power use.} $
- Option C: The graph is cost per hour, not monthly cost (depends on usage time). Eliminate C.
- Option D: Higher cost per hour (Appliance 1) implies higher current (if voltage constant), so D is wrong.
# Answer:
B. Appliance 1 uses the most power.

### Question 3
# Brief Explanations:
- Conductors allow current, insulators prevent.
- Silver and copper are good conductors; plastic, rubber, glass, sand are insulators (or poor conductors).
- Option D: Silver (conductor) and plastic (insulator) fit: silver conducts, plastic insulates for safety.
- Other options: Glass (insulator), sand (insulator), silver (conductor can't insulate) are wrong.
# Answer:
D. silver to conduct and plastic to insulate

### Question 4 (Assuming the question is about fuse preventing electrical fire)
# Brief Explanations:
- Fuses work by melting when current is too high (overload), breaking the circuit to prevent fire.
- Option B: "by melting if the current gets too high" matches.
- A: Grounding is for safety, not fuse. C: Fuses don't reduce voltage. D: Fuses don't store energy.
# Answer:
B. by melting if the current gets too high

### Question 5
# Brief Explanations:
- Charging by friction transfers electrons between objects.
- Option A: Electrons transfer from one to another (correct).
- B: Electrons don't disappear. C: Charge separation, not sudden negative. D: Electrons aren't created, transferred.
# Answer:
A. Electrons are transferred from one object to another.

### Question 6 (Constructed Response)
# Explanation (Brief):
- Lightning can't power a cell phone because it's a short, high - voltage, high - current discharge (not a stable source). A 6 - volt battery provides stable, low - voltage, appropriate - current power.
- Using Ohm's Law $ I=\frac{V}{R} $: A 100 - million - volt battery connected to a cell phone (low $ R $) would produce extremely high current ($ I=\frac{100000000}{R} $, $ R $ of cell phone is small), causing overheating, damage, or fire.
# Answer (Brief):
Lightning is an unstable, high - energy discharge (not a controlled power source) with very high voltage and current in a short burst, unsuitable for powering a cell phone (needs stable, low - voltage, appropriate - current power like a 6 - V battery). A 100 - million - volt battery connected to a cell phone would, by Ohm’s Law ($ I = \frac{V}{R} $), produce an extremely large current (since the cell phone has low resistance $ R $), leading to massive overheating, destruction of the cell phone, and potential fire or electrical hazards.

Sovi.AI - AI Math Tutor

QUESTION IMAGE

Question

Explanation:

Question 2

Step1: Recall Ohm's Law

Step2: Substitute Values

Step3: Calculate Current

Answer:

Question 1