Chapter 67 science

What unit is resistance measured in?

Ohm

What law states that current is equal to the voltage difference divided by the resistance?

Ohm's law

What is a path that allows only one route for an electric current called?

Series circuit

What do we call electric charge that has accumulated on an object?

Static electricity

What kind of circuit has two or more branches for electrons to follow?

Parallel circuit

What is the rate at which an electrical device converts energy called?

Electrical power

What is a material through which electrons do NOT easily flow?

Insulator

What does it indicate if the leaves of an electroscope spread apart?

The leaves have received a charge.

What is a large discharge of static electricity called?

Lightning

What role does the carbon rod in a standard D-cell play?

It serves as a conductor to transfer electrons.

What is one source of constant electric current?

A dry cell

What is the relationship among power, current, and voltage?

P = I × V

What equation calculates electrical energy?

E = P × t

What device is designed to open an overloaded circuit to prevent overheating?

Circuit breaker

What do electric forces cause objects to do?

Repel or attract each other.

If rods P and Q repel each other and P and R attract, what can we say about their charges?

P and Q have like charges, P and R have opposite charges.

What does conservation of charges mean?

The total charge before and after charging remains the same.

When a conducting sphere is charged positively, how does the charge distribute on the surface?

It spreads uniformly throughout the surface.

What is conduction in terms of charging?

Charging a neutral body by touching it with a charged body.

What is induction in terms of charging?

Charging an object without touching it with a charged body.

What is true about electric forces compared to gravitational forces?

Electric forces can be either repulsive or attractive, while gravitational force is always attractive.

What do like charges do to each other?

Repel.

What do opposite charges do to each other?

Attract.

What is an insulator?

A material where charges will not move easily.

What is a conductor?

A material that allows charges to move about easily.

What is true about electrical and gravitational forces?

Electrical forces are enormous compared to gravitational forces.

What charge does an area with excess electrons have?

Negative charge.

What charge does an area with a deficit of electrons have?

Positive charge.

Why are atoms normally electrically neutral?

They have equal numbers of protons and electrons.

What is the current flow equal to one coulomb per second called?

Ampere.

How do you describe a dry-cell battery's current?

It produces a direct current.

What is the function of an electric motor?

To change electrical energy to mechanical energy.

What is the function of a transformer?

To increase or decrease voltage in a power line.

What device uses an electromagnet to measure electric current?

Galvanometer.

What are the locations of the strongest magnetic forces called?

Magnetic poles.

What is the region around a magnet where the magnetic forces act called?

Magnetic field.

What happens to the magnetic domains in a magnet?

They align according to magnetic fields.

What type of circuit has a single current path?

Series connection.

What type of circuit has multiple paths for current?

Parallel circuit.

What is the output voltage of a step-up transformer with 250 turns in the primary coil and 7000 turns in the secondary coil?

The output voltage is higher than the input voltage.

What voltage does a step-down transformer reduce for home use?

120 V.

What happens when you break a magnet into two?

You get two north poles and two south poles.

What does changing the current do to an electromagnet?

It changes the strength and direction of the electromagnet.

What is a magnetic field?

The region around a magnet where magnetic forces act.

What can an electric motor convert energy into?

Kinetic energy.

What does a galvanometer measure?

Currents.

In a step-up transformer, which coil has more turns?

The secondary coil.

What is the primary coil's relation to the secondary coil in a step-down transformer?

It has more turns than the secondary coil.

How does electromagnetic induction occur?

By moving a loop of wire through a magnetic field.

What is direct current?

Current that does NOT reverse direction.

What do you get if you charge two objects that attract each other?

A positive and a negative charge.

What is the resistance measured in?

Ohms.

How do you calculate power?

P = I × V.

What happens to the current if voltage and resistance are both halved?

The current remains unchanged.

What is the effect of a battery on a lightbulb connected to its terminals?

It produces a power consumption measured in watts.

What happens if the voltage of the source is higher than the resistance?

Current will flow through the circuit.

What is measured in kilowatt-hours?

Electric energy use by power companies.

What role does a resistor play in a circuit?

It controls the current.

What is a lightbulb that uses 15 W of power connected to 25 V?

Current through the lamp is calculated by P = I × V.

How many times does an ampere represent one coulomb of charge per second?

It denotes a measurement of electric current.

What converts mechanical energy to electrical energy?

A generator.

What is the output voltage of a transformer with 7000 turns in the secondary and 250 turns in the primary if the input is 18.0 V?

504 V.