Key things you must know

Question 1

Define the decay constant λ

Answer 1

The decay constant λ of a radioactive nuclei is the probability that an individual nucleus will decay within a unit of time.

Question 2

Define the activity A

Answer 2

The activity A of a source is the number of its nuclei that decay in unit time.

Question 3

Define half life T₁/₂

Answer 3

The half life T₁/₂ is the time taken for half the radioactive nuclei to decay.

Question 4

Define the distance of closest approach

Answer 4

The distance of closest approach is defined as the distance from a charged particle to the centre of the nucleus at which the whole of the kinetic energy of the charged particle gets converted into electrical potential energy of the system.
its gives an estimate for the maximum value of the nuclear radius.

Question 5

What two equations can be used to estimate nuclear radius?

Answer 5

R = R₀A^1/3

Where:
* R = Radius of nucleus
* R₀ = Constant = 1.4fm
* A = Nucleon number

Question 6

What is Kepler’s First Law?

Answer 6

The orbit of a planet is an ellipse, with the Sun at one of the two foci

Question 7

What is Kepler’s Second Law?

Answer 7

A line segment joining the Sun to a planet sweeps out equal areas in equal time intervals

Question 8

What is Kepler’s Third law?

Answer 8

The square of the orbital time period T is directly proportional to the cube of the orbital radius r
T2 ∝ r3

Question 9

What is Faradays law?

Answer 9

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

Question 10

What is Lenzs law?

Answer 10

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