Electric Forces and Charges
What happens to the net charge of an object when negative charges are transferred to it?
The net charge becomes more negative.
Why do all magnets have a north and south pole?
Because the alignment of magnetic domains creates two poles in every magnet.
What is a field in science?
An area in which a force that acts at a distance can be detected.
How does the mass of objects affect the gravitational force between them?
Greater mass increases the gravitational force.
How does gravity affect the shape of large celestial bodies?
Gravity pulls matter evenly toward the center, forming a mostly spherical shape.
Why do opposite charges require a force to be separated?
Because opposite charges attract each other.
What generates a magnetic field around a wire?
A moving electric charge or current through the wire.
How do electric fields differ from gravitational fields in how they affect objects?
Electric fields affect charged objects, while gravitational fields affect objects with mass.
How does increasing the distance between two objects affect the gravitational force?
Increasing distance decreases the gravitational force.
What keeps satellites in orbit around Earth?
The gravitational force between the Earth and the satellite.
How does friction between two materials affect electric charges?
Friction increases the rate at which charges separate.
How does a solenoid make a magnetic field stronger?
By looping the wire into multiple coils, concentrating the magnetic field.
Why do field strengths decrease with distance?
Because the influence of the source spreads out over a larger area.
Why do all objects near Earth fall at the same rate, regardless of mass?
Because the acceleration due to gravity is the same for all objects near Earth.
How does velocity affect the motion of a projectile?
The direction and speed change depending on the direction of acceleration relative to the velocity.
What determines whether electric forces push or pull on objects?
The signs of the electric charges (like charges repel, opposite charges attract).
What is electromagnetic induction?
The process of generating a current by a changing magnetic field.
What is the main difference between force arrows and field lines?
Force arrows show the direction of a noncontact force, while field lines show the uniformity and shape of the field.
Why is gravity considered a noncontact force?
Because it acts between objects without them touching.
What role did Newton play in explaining planetary motion?
He developed a model of gravity that explained the motions of planets based on mass and distance.
What is the difference between static electricity and electric current?
Static electricity involves charges that are not moving, while electric current is a continuous flow of charges.
Under what condition will a current not be induced when both a magnet and wire are moving?
If both the magnet and wire move at the same velocity in the same direction.
Can a magnetic force be both attractive and repulsive?
Yes, depending on the orientation of the magnet poles.
What is the relationship between mass, distance, and gravitational force in Newton’s law of universal gravitation?
Force is proportional to the product of the masses and inversely proportional to the square of the distance between them.
Why can light not escape from a black hole?
Because the gravitational force at its surface is extremely strong.