A couple physics questions if someone is willing to help?
I have 8 physics questions that I can’t quite figure out the answers for, if anyone would be willing to share the answers, that would be awesome.
1.) Is it possible to have a zero electric field value between two positive charges along the line
joining the two charges?
A) Yes, if the two charges are equal in magnitude.
B) Yes, regardless of the magnitude of the two charges.
C) No, a zero electric field cannot exist between the two charges.
D) cannot be determined without knowing the separation between the two charges
2.) An atomic nucleus has a charge of +40e. An electron is 10-9 m from the nucleus. What is
the force on the electron?
A) 2.9 nN
B) 1000 C
C) 3.7 nN
D) 6.8 nN
E) 9.2 nN
3.) What fundamental fact underlies the operation of essentially all electric motors?
A) Opposite electric charges attract and like charges repel.
B) A current-carrying conductor placed perpendicular to a magnetic field will experience a force.
C) Alternating current and direct current are both capable of doing work.
D) Iron is the only element that is magnetic.
E) A magnetic north pole carries a positive electric charge, and a magnetic south pole carries a
negative electric charge.
4.) An object is placed 15 cm from a concave mirror of focal length 20 cm. The object is 4.0 cm
tall. Where is the image located?
A) 12 cm behind the mirror
B) 12 cm in front of the mirror
C) 60 cm behind the mirror
D) 60 cm in front of the mirror
5.) The energy difference between adjacent orbit radii in a hydrogen atom
A) increases with increasing values of n.
B) decreases with increasing values of n.
C) remains constant for all values of n.
D) varies randomly with increasing values of n.
6.) How much energy is carried by a photon with frequency 110 GHz?
A) 1.1 × 10-20 J
B) 1.4 × 10-22 J
C) 7.3 × 10-23 J
D) 1.3 × 10-25 J
7.) Suppose that the speed of an electron traveling 2000 m/s is known to an accuracy of 1 part
in 105 (i.e., within 0.001%). What is the greatest possible accuracy within which we can determine
the position of this electron?
A) 2.9 mm
B) 5.8 mm
C) 8.7 mm
D) 1.2 cm
8.) When nucleons join to form a stable nucleus, energy is
A) destroyed.
B) absorbed.
C) released.
D) not transferred.
Any help would be greatly appreciated.
One Response
Michael
31 May 2010
You’ll have better luck getting better answers to these questions if you posed them as 8 separate questions. That way, responders could earn 80 points, not just 10. You’d be increasing the incentive 8 times. Also, people don’t like writing really long answers.
To get you started, the answer to 1 is B). If you consider a point between two positive charges, the field from the left charge will point to the right and the field from the right charge will point to the left. Regardless of the magnitude of these two charges, you can always find a spot closer to the smaller charge where those two fields will cancel out. If you are right on top of a charge, the electric field will be close to infinity. The math will always work out.