Question

QUESTION 1

1. If you wanted to double the momentum of a photon you would

   	1.	double its velocity.
   	2.	double its mass.
   	3.	double either its mass or its velocity.
   	4.	double its wavelength.
   	5.	decrease its wavelength by a factor of two.

2. In the photoelectric effect, if we double the intensity of the beam of light which has a frequency below the cutoff frequency,

   the number of electrons ejected per second will

   	1.	double.
   	2.	go up by factor of four.
   	3.	be cut in half.
   	4.	go down by a factor of four.
   	5.	remain zero.

3. The de Broglie hypothesis is that

   	1.	nothing can move faster than the speed of light
   	2.	charge is quantized within the nucleus of an atom
   	3.	waves can have particle like properties and particles can have wave like properties
   	4.	energy is neither created or destroyed except in quantized pieces within limited time periods

4. Following the calculations given in Active EXample 30-2, how fast is an

   electron moving if its de Broglie wave length is 2 X10 ^-7 meters

   long?

   	1.	4731 m/sec
   	2.	4367 m/sec
   	3.	4003 m/sec
   	4.	3639 m/sec
   	5.	3275 m/sec

5. The photoelectric effect happens when

   	1.	any electrical current is used to create light.
   	2.	any alternating electrical current is used to create light.
   	3.	alternating current is used to create light in the ultraviolet wave range.
   	4.	a beam of light hits a surface of a metal and ejects an electron.
   	5.	a beam of electrons hits a surface of a metal and releases light.

6. You can increase the energy of a beam of light by increasing its

   	1.	wave length
   	2.	frequency
   	3.	both of the above
   	4.	none of the above

7. If you were to double the temperature of the surface of a star, the frequency at which its

   radiation peaked would

   	1.	double
   	2.	go up by a factor of 4
   	3.	go down by a factor of 2
   	4.	go down by a factor of 4
   	5.	remain the same

8. The reason an electron microscope can see much finer detail of a small object

   than a light microscope is because

   	1.	the wave length of the electrons is much smaller than the wave length of visible light
   	2.	electrons have a negative charge which is attracted to the nucleus of the atoms.
   	3.	electrons have a negative charge which is repelled by the electrons surrounding the nucleus.
   	4.	electrons have a small quantum mechanical spin which allows it to move around the corners of the object.

9. Following the method shown in Example 30-6, what would be the uncertainty in the

   position of a 145 gram baseball if its speed were 25 meter/sec with an uncertainty of

   5% ?

   	1.	5.82 X 10-34 m
   	2.	6.40 X 10-34 m
   	3.	6.98 X 10-34 m
   	4.	7.57 X 10-34 m
   	5.	8.15 X 10-34 m

10. When a quantum particle passing through a small region of space which would

    be forbidden if it were a classical particle, this is referred to as

    	1.	internal refraction.
    	2.	quantum jumping.
    	3.	phase diffraction.
    	4.	quantum tunneling.

Answer 1

Answer:a) 5.Momentum of a photon is given as p = h/ where h is planck's constant and is wavelength.

So, due to the inverse relation, reducing the wavelength by factor of 2 would increase the momentum by factor of 2.

b) 5. Number of ejected photons are zero if Energy or frequency of hitting photons is below the cutoff value since the phenomenon is of a one to one collision.So, increasing the intensity i.e. the number of photons won't be able to eject even a single electron.

c) 3. The De Broglie hypothesis states that wave and particle are two sides of the same coin where a wave collapses when it is disturbed to behave like a particle.

d) 4.The de broglie wavelength is given by = h/p where h is planck's constant.

So, p = h/ = mv

So, v = h//m = 6.626*10^-34/2/10^-7/9.1/10^-31 = 3639 m/s

e) 4.The photoelectric effect happens when a beam of light hits a surface of a metal and ejects an electron in a one to one collision.