physics laws and definitions

Question 1

what is Kirchhoff’s first law?

Answer 1

total current entering a junction=total current leaving it

Question 2

what is Kirchhoff’s second law?

Answer 2

total e.m.f around a series circuit= sum of p.d.s across each component

Question 3

what is Lenz’s law?

Answer 3

The direction of the induced emf is always in such a direction as to oppose the change that caused it

Question 4

what is Faraday’s law?

Answer 4

induced emf is directly proportional to the rate of change of flux linkage

Question 5

Define the electric field strength at a point in an electric field

Answer 5

• is the force per unit charge

- On a (small) positive charge (at that point)

Question 6

State what is represented by gravitational field lines

Answer 6

• ## Gravitational field lines show the direction of force on a mass

Question 7

Define the gravitational potential at a point.

Answer 7

• the work done per unit mass

- in moving from infinity to the point

Question 8

Define gravitational field strength and state whether it is a scalar or vector quantity.

Answer 8

• force per unit mass

- a vector quantity

Question 9

what is Coulomb’s law?

Answer 9

f=q1q2
4piEr^2
gives the force of attraction or repulsion between two point charges

Question 10

what is Boyle’s law?

Answer 10

at constant temperature, pressure and volume are inversely proportional

Question 11

what is Charles’ law?

Answer 11

at constant pressure volume is directly proportional to temperature

Question 12

what is the pressure law?

Answer 12

at constant volume the pressure is directly proportional to the temperature

Question 13

what is flux linkage?

Answer 13

a magnetic field going through a coil of wire equal to the flux times the number of coils in the wire

Question 14

what is angular velocity?

Answer 14

rate of change of angular displacement with respect to time swept out by the radius