Novare Physical Science Ch. 5 Objectives

Name the three fields that are part of basic physics

1. Gravitational Field 2. Electric Field 3. Magnetic Field

Compare the strengths of the four fundamental forces

1. Strong nuclear force: 10 to 38th power stronger than gravitational force; 10 trillion times stronger than the weak nuclear force 2. Electromagnetic force: 10 to 35th power stronger than gravitational force 3. Weak nuclear force: 10 to the 13th power stronger than the gravitational force; 10 trillion times weaker than strong nuclear force 4. Weakest force

List the four fundamental forces (or fundamental interactions) found in nature.

1. gravitational force 2. electromagnetic force 3. strong nuclear force 4. weak nuclear force

How does an electromagnet work?

A magnetic formed by winding a wire into a coil and passing a current through it. Electromagnets have a north and south pole. They typically wrap around a steel core. The iron core increases the strength of the magnetic field considerably. If the current is flowing in a coil of wire, the strength of the electromagnet is also proportional to the number of turns of wire in the coil.

State Ampere's Law

An electric current generates a magnetic field that is proportional to the strength of the current. If the current is flowing in a coil of wire, the strength of the magnetic field is also proportional to the number of turns of wire in the coil.

Who is Marie Curie? - When & where was she born? - What is she known for?

Born in 1891 in Warsaw, Poland; moved to Paris at 24 yrs. old & remained there. - One of the most famous women in the history of science - First woman to win a Nobel Prize & first person to win two Nobel Prizes, one of only two people to win Nobel Prizes in 2 different fields. - Coined the term "radioactivity," discovered the elements radium & polonium, first to isolate pure radium.

What are the key features of the Electric Field? - What causes the them? - What is affected by them? - How are they shaped? - What is the strength of the electromagnetic force compared to the gravitational force?

Cause: Any charged object Affected by EF: Any charged object (protons, electrons, clusters of protons, clouds of electrons) Anything without charge are NOT affected by this force. (neutrons, equal amount of protons & electrons, equal amount of positive/negative charge) Shape: For a spherical charge distribution, the direction of the force of the field is toward or away from the center of the charge. A flat sheet of charge produces a uniform field. Strength: the electromagnetic force is 10 to 36th power times that of the gravitational force.

What are the key features of the gravitational field? - What causes the them? - What is affected by them? - How are they shaped?

Cause: Anything with mass (matter) Affected by GF: Any physical object with mass (matter; made of atoms) & electromagnetic radiation (light) will be affected by this force. Anything without physical atoms will not be affected (memories, thoughts, HS, love). Shape: The direction of the force of the field is toward the CENTER of the object causing the field.

What are the key features of the Magnetic Field? - What causes them? - What is affected by them? - How are they shaped?

Cause: Magnets, current-carrying wires Affected by MF: Magnetic fields affect other magnets, wires carrying electric current, moving charged particles, and any object with iron in it. Typically objects without iron will not be affected. Shape: Field lines around a magnet go from north pole to south pole. Field lines around a current-carrying wire are arranged in concentric circles. Magnetic poles always come in pairs - there is no magnetic monopole.

What is the gravitational theory of Isaac Newton? When was it published?

In 1687, Newton published the Law of Universal Gravitation. He proposed that everything in the universe that had mass (all matter) exerted gravitational force on everything else in the universe that had mass.

What is the gravitational theory of Albert Einstein? When was it published?

In 1915, Einstein published the general theory of relativity. Einstein envisioned gravity as geometrical in nature, and proposed the presence of any massive body warps the dimensions of space and time around itself. This gave a reason for WHY bodies exert gravitational attraction on one another. The gravitational forces is the curvature of spacetime. According to his theory, the spacetime around any massive object is warped. This means that even light, though massless, will be affected by it.

Compare the strengths of the four fundamental forces

The STRONGEST force is the strong nuclear force. The WEAKEST force is the gravitational force.

Explain how an inverse-square law works.

When a force varies according to an inverse square law, the force strength is inversely proportional to the square of the distance between two objects. So if the force between two objects is one newton when they are 1m apart, when they are 2m apart they are twice as far apart but the force between them will be one over four times as great, 1/4 times as much.