Friday, November 20, 2015

GCE Advanced level Physics questions on SIMPLE HARMONIC MOTION ELECTROMAGNETIC INDUCTION NUCLEAR PHYSICS QUANTUM PHYSICS GRAVITATIONAL FIELD ELECTRIC FIELDS












 

GCE Advanced level Physics questions  on
SIMPLE HARMONIC MOTION
ELECTROMAGNETIC INDUCTION
NUCLEAR PHYSICS
QUANTUM PHYSICS
GRAVITATIONAL FIELD
ELECTRIC FIELDS








SIMPLE HARMONIC MOTION

1.       
a.        
(i)      
Explain what is meant by simple harmonic motion
(2marks)


(ii)    
Sketch graphs showing how the following quantities vary with the period of oscillation for one complete cycle.
-          Kinetic energy
-          Potential energy
-          Total energy
(5marks)

b.       

A pendulum bob of length 1.2m has a bob of mass 0.2g. The bob is pulled aside a horizontal distance of 20.0cm and then released.
Calculate



(i)      
The velocity of the bob at its lowest point.
(3marks)


(ii)    
The maximum kinetic energy of the bob.
(2marks)






c.        

Mechanical systems may undergo free, damped and forced oscillations.




Explain the meaning of the underlined words
(3marks)






d.       

The displacement x in m, form the equilibrium position of a particle moving with SHM is given by
     Where t the time measured in s, and measured from an instant when x=0.



(i)      
State the amplitude of the oscillation
(1marks)


(ii)    
Calculate the time period of the oscillations
(2marks)


(iii)  
The maximum acceleration of the particle.
(2marks)



OR




ELECTROMAGNETIC INDUCTION







e.        
(i)      
State the laws of electromagnetic induction
(4marks)


(ii)    
Define electromagnetic induction
(2marks)


(iii)  
Explain the origin of the back emf in an electric motor
(3marks)








The flux density between the poles of a powerful electromagnet is 2.5T. what is the force exerted on 15mm of wire carrying a current of 3.0A when the wire is


f.        
(i)      
At right angles to the field
(2marks)


(ii)    
Parallel to the field
(1marks)


(iii)  
At an angle of 30o to the field
(2marks)






g.        

A coil of L = 30mH and a resistance R = 5Ω is connected in series with a capacitor C. An a.c supply connected across them gives 12V rms at 40Hz



(i)      
Calculate the value of C at resonance
(2marks)


(ii)    
Calculate the rms current at resonance
(2marks)


(iii)  
Calculate the rms pd across the coils at resonance
(2marks)








Answer either 2 (a),(b),(c) and (d) or  2(e), (f) (g)





  NUCLEAR PHYSICS






2.       
a.        
(i)                  
State the observations obtained from the Rutherford alpha scattering experiment with a thin metal foil.
What conclusions may be deducted from each of these observations
(6marks)


(ii)                
Explain how and why the masses of compound differ from the sum of the masses constituent particles
(2marks)






b.       

Radium (Ra) decays to radon (Rn) by the reaction







(i)      
Estimate the energy released in joules when an atom of Ra decays



(ii)    
Estimate the wavelength of gamma photon emitted during this decay given that 4% of the energy released turns to gamma radiation



(iii)  
What happens to the remaining 96% of the energy









The atomic masses of radium = 3.753 x 10-25kg, radon = 3.686 x 10-25kg , helium = 0.066 x 10-25kg
(8marks)






c.        

An alpha – particle is accelerated to attain a kinetic energy of 1.34 x 10-15kJ collides head on with a gold nucleus. Calculate the upper limit of the radius of gold nucleus.   (the proton number of gold is 79)
(4marks)








Planck constant   ,   




OR




QUANTUM PHYSICS







d.       

Electrons can be emitted from the surface of zinc by ultra violet light nut by visible light. On the other hand, electrons can be emitted from potassium even by visible light.



(i)      
Explain why visible light cannot cause electrons to be emitted from the surface of zinc whereas ultraviolet light.
(2marks)


(ii)    
If both metals were illuminated with ultraviolet light of the same frequency, how will the energies of electrons emitted from the zinc and potassium surface differ
(2marks)






e.        

Explain each of the following



(i)      
If the intensity of the violet light directed at a piece of zinc is double, the number of electrons leaving the surface per second also doubles but the maximum kinetic energy is uncharged.
(4marks)


(ii)    
The maximum kinetic energy of photoelectrons is directly proportional to the difference between the frequency of light falling on the surface and the threshold frequency for that metal
(4marks)


(iii)  
Gamma photons are more harmful to people than infrared photons
(3marks)






f.        

Calculate the wavelength of the photon emitted when an electron makes a quantum jump from the n= 3 state to the ground state of the hydrogen atom. The energy state of the state n=3 is -1.52eV and that at the ground state is 13.6eV.
(5marks)








Choose one question  from either question  3, 4 or 5





ENERGETICS






3.       
a.        
(i)      
Distinguish between specific (latent) heat of vaporization and latent heat of vaporization.
(4marks)


(ii)    
Describe and experiment to determine the specific latent heat of vaporization of water
(7marks)






b.       

An electric heater rated at 2.0W is used to heat 15g of water in a copper kettle. The initial temperature of the water is 20oC.



(i)      
What time does it take to heat the water to its boiling point
(3marks)


(ii)    
Calculate the mass of water that would have boiled away in five minutes
(3marks)






c.        

Estimate how long it would take all the water to evaporate. State any assumptions that you make in your calculations.
(3marks)








Specific heat capacity of water is 4200Jkg-1K-1




Heat capacity of copper is 400 JK-1









GRAVITATIONAL FIELD






4.       
a.        
(i)      
State Newton’s law of gravitation
(2marks)


(ii)    
State Kepler’s laws of planetary movement
(3marks)


(iii)  
Determine the dimension of the universal gravitation constant G
(2marks)

b.       

Derive an expression for the acceleration g, due to gravity at the earth’s surface in terms of G, the radius of the earth R and its density,
(4marks)

c.        

Calculate the escape velocity of the earth given that
 Radius of earth, R = 6.4 x 106m,
(3marks)

d.       

A communication satellite revolves round the earth in a circular orbit at a height of 36000km above the earth’s surface. Fine the satellite’s period of revolution in hours. Comment on the results.
Radius of earth, R = 6.4 x 106m, G =6.7x10-11 Nm2kg-2 ,mass of the earth M =
(7marks)








ELECTRIC FIELDS






5.       
a.        
(i)                  
State coulomb’s law 
(2marks)


(ii)                
The variation of the force (F/N) between a pair of equally charged molecules in a medium with the inverse square of the distance r them is shown in the graph below


Fig 1
Fig 2



Use the graph to obtain a value for the permittivity of the medium, given that each charge is 4x10-3C
(4marks)






b.       

Sketch separate graphs showing the how the electric field strength E  and electric potential V varies with distance r, from the Centre of a uniform solid metal sphere of radius ro which is positively charged.
(4marks)






c.        

A 10uF capacitor is charged from a 30V supply and then connected across an uncharged 50uF capacitor as shown on fig 2.



(i)                  
What is a capacitor
(1marks)



Calculate the



(ii)                
The initial charge stored on the 10uF capacitor
(1marks)


(iii)              
The final p.d across each capacitor
(1marks)


(iv)              
The final charge on each capacitor
(1marks)