Quick Quiz
What are the seven basic physical quantities?
answer
Temperature (K)
Length (m)
Luminous intensity (Cd)
Mass (kg)
Number of particles (moles)
Time (s)
Charge (C)
What is meant by the "half-life" of a radioactive substance?
answer
Half-life is the time taken for half the
number of a specific type
of radioactive nuclei to decay. It is constant.
dN/dt = -kN
therefore by integration, N = Noe^(-kt)
lnN = lnNo - kt
lnNo - lnN = kt
Now, when N = No/2, ln2 = kt½
thus t½ = ln2/k
where k is the decay constant, N is the
number or mass of
radioactive nuclei at time t, No is N at t=0.
What is a Tesla?
answer
A Tesla (T) is a unit of magnetic field strength.
It is the magnetic field strength required to produce a
force of 1 N on a charge of 1 coulomb
travelling 1 m/s perpendicularly to the magntic field.
What are some useful equations concerning uniformly accelerating bodies?
answer
1. v = u + at
2. v² = u² + 2as
3. s = ut +
½
at²
