Science Electricity And Magnetism Test

25 July 2022
4.7 (114 reviews)
65 test answers

Unlock all answers in this set

Unlock answers (61)
question
Describe one way that the force of gravity and magnetic force are similar. Describe one way they are different.
answer
A similarity is they both exert force in their similar form. A difference is gravity always attracts, magnets attract and repel.
question
Explain how there can be electrical charge inside matter even if it shows no electrical forces.
answer
Atoms are made with equal amounts of positive and negative electricity charges so the attraction holds all the atoms in the mass together to hide the electric charge inside a state of mass.
question
List one way electric current is similar to water current and one way that it is different.
answer
They can both carry energy within themselves and do work. A difference is if a water pipe is open, water will leak out, if you cut open a current, it can't leak out.
question
Explain the difference between an object that has "static electricity" and one that does not.
answer
On a dry day if you touch an object that contains static electricity, you can get shocked, but with a different object you cannot be shocked.
question
List the units for measuring current, voltage, and resistance
answer
Voltage- volts Current- Amperes (amps) Resistance- Ohms
question
Describe the difference between current and voltage. Can there be voltage without current? Can there be current without voltage?
answer
Current flows while voltage provides the energy for the current flow. There can be voltage without current but you can't have a current without voltage.
question
Electrical current flows:
answer
From positive to negative
question
An electrical circuit is:
answer
A path for electric current to flow
question
What is the difference between water in pipes and current in wires?
answer
Water leaks out of open pipes but current does not leak out of open wires.
question
How much electrical power is carried by 2 amps of current from a 1.5-volt battery?
answer
3 watts
question
How much current must flow to carry 240 watts at 120 volts?
answer
2 amps
question
Which carries more power: 100 amps at 12 volts or 10 amps at 120 volts? (Hint: Is one more, or are they equal?)
answer
They are equal
question
What happens to the current if a circuit's resistance increases?
answer
It will decrease
question
What happens to the current if a circuit's resistance decreases?
answer
It will increase
question
List the units used to measure resistance , voltage, and current. Give the abbreviation for each unit.
answer
Resistance - R (Ohms) Voltage - V (Volts) Current - I (Amps)
question
Classify each of the following as a conductor, semiconductor, or insulator: air, gold, silicon, rubber, and aluminum. Air- Gold- Silicon- Rubber- Aluminum-
answer
Air- insulator Gold- conductor Silicon- semiconductor Rubber- insulator Aluminum- conductor
question
Which magnetic pole is attracted to a south magnetic pole?
answer
North magnetic pole
question
Why can the magnetic force be either attractive or repulsive when gravity can only be attractive?
answer
Because 2 of the same poles repel each other and you can switch magnetic poles.
question
Name two materials which are magnetic and two that are not magnetic.
answer
Magnetic: Safety pins, paper clips Non-Magnetic: fabric, plastic
question
A compass points north because
answer
It is facing earth's south magnetic pole.
question
Why does a compass change direction when it is near a current-carrying wire?
answer
The compass is attracted to the wire because the wire is a conductor.
question
What is the difference between a permanent magnet and an electromagnet?
answer
An electromagnet is caused by electricity and can be switched on and off, and a permanent magnet is magnetic without any energy.
question
Iron attracts
answer
both north and south poles of a magnet
question
An electric generator uses changing magnetism to
answer
induce current to flow in a coil
question
2 kinds of electric charge
answer
positive and negative
question
2 magnetic poles
answer
North and South
question
The flow of tiny particles that carry electrical energy is called
answer
an electric current
question
The unit of measure for electric current is
answer
amp
question
A complete path through which electric current is
answer
an electric circuit
question
A(n) _________ has a high electrical resistance
answer
insulator
question
The physical law relating electrical resistance is called a(n) ___________
answer
Ohm's Law
question
A material, such as copper, with low electrical resistance is called a(n) ____________
answer
conductor
question
A magnet made using wires and electric current is an ____________
answer
electromagnet
question
Materials similar to iron that have strong magnetic properties are called ____________
answer
ferromagnetic
question
The influence created by a magnet that exerts forces on other material objects is known as a(n) _____________________
answer
Magnetic Field
question
A scientist says, "Magnetic poles of magnets and electric charges on bodies apply forces in similar ways." Explain what is meant by this statement.
answer
They have similar effects on the object
question
Why is it more difficult to determine the electric charge on an object than the mass of an object?
answer
Electric charge is well hidden inside atoms, unlike mass.
question
Explain how a cat's fur may become statically charged.
answer
Static electricity comes from dry air. When a cat rubs against blankets, couches, carpets, etc., static accumulates on their fur. This happens because the cat is picking up excess negative charge that moves to the fur, and makes it stand.
question
How does static electricity differ from current electricity?
answer
Static electricity is a tiny imbalance between positive and negative charge on an object, and current electricity is a flow of tiny particles that carries electrical energy in wires and machines.
question
Why don't you usually notice electric forces between objects?
answer
You cannot see electric forces
question
How does voltage cause current to do work?
answer
Voltage provides power/energy for current to move.
question
What does a battery do in an electrical circuit?
answer
A battery provides the voltage, which provides the power/energy to make the current flow.
question
Explain the difference between an open circuit and a closed circuit?
answer
An open circuit is a circuit with a break in it, causing the current to stop flowing. A closed circuit is a circuit that is complete without a broken path.
question
Will a bulb light in an open circuit? Why or why not?
answer
No, because the current will not flow to the bulb, so the bulb will have no power to light.
question
Is flipping a switch the only way to create an open circuit?
answer
No, any kind of break in the circuit can cause an open circuit.
question
How are volts, amps, and watts related?
answer
Volts are in the battery which provided power/energy, amps measure the current, and watts measure the power of the current.
question
Explain how volts, amps, and ohms are related in a circuit.
answer
Volts provide power for the amps and the amps bring the energy to a light bulb and the light is measured in ohms.
question
Why is it more dangerous to touch a wire conducting electric current with wet hands than with dry hands?
answer
Water is a conductor, so when touching an electric current with wet hands, it could electrocute you, dry hands have more resistance.
question
How does the force between two magnets differ from the force between two masses?
answer
Two magnets attract or repel each other, and two masses don't attract or repel each other.
question
Large, electromagnetic cranes are used in junk yards for moving scrap metal from one location to another. Why would an electromagnet be more useful in this application than a permanent magnet?
answer
Electromagnets are stronger than permanent magnets, and in a junk yard you are moving big items, so you want a more powerful magnet.
question
Suppose you stick a magnet on the door of your refrigerator. Is the magnet a magnetic material or a permanent magnet? Is the refrigerator door a magnetic material or permanent magnet?
answer
The refrigerator door is a magnetic material, and the magnet is a permanent magnet.
question
Two magnetic north poles _______ each other. Two south poles ________ each other. A north pole and a south pole __________ each other.
answer
repel; repel; attract
question
Magnetic field lines outside a magnet point away from its _______ pole and toward its _______ pole.
answer
North; South
question
Explain how to make current flow in a wire coil using a magnet.
answer
A battery provides energy for the current to flow, so you change to magnet to an electromagnet.
question
Compare an electric motor to an electric generator.
answer
Electric motors transform electric energy into mechanical energy and electric generators transform mechanical energy into electrical energy.
question
What happens when two positively charged objects are placed near each other?
answer
They will repel each other
question
Four 1.5-V AA batteries are connected end-to-end. 1) What is the voltage difference across a single battery? 2)What is the voltage difference across two batteries? 3) What is the voltage difference across all four batteries?
answer
1.5 volts; 3 volts; 6 volts
question
Household circuits in the United States typically run on 120 volts of electricity. Circuit breakers are commonly used to break a circuit if the current is greater than 15 amperes. What is the minimum amount of resistance needed in a circuit to prevent the circuit breaker from activating?
answer
8 ohms
question
A hair dryer draws a current of 10 A when plugged into a 120-volt outlet. What is the resistance of the hair dryer?
answer
12 ohms
question
Calculate the current produced if a 12-volt battery supplies 6 watts of power
answer
0.5 amps
question
A television runs on 120 volts and has a resistance of 60 ohms. What current does it draw?
answer
2 amps
question
The current flowing through a 1,200-watt hair dryer is 10 amperes. Calculate the voltage that must be supplied to operate this hair dryer properly.
answer
120 volts
question
When you plug in a cell phone, a transformer on the plug changes the outlet's 120 volts to the 6 volts needed by the battery. The transformer draws 1 amp of current from the electrical outlet. 1) How much power does the wall outlet supply to the transformer? 2) What current does the telephone draw?
answer
6 volts; 1 amp
question
What is a joule?
answer
The amount of energy exerted when a force of one newton is applied over a displacement of one meter. One joule is the equivalent of one watt of power radiated or dissipated for one second.
question
What is the formula to find power?
What is the formula to find power?
answer
P = I x V I = P / V V = P / I