A proton beam that carries a total current of 1.3 mA has 10.0 mm diameter. The current density in the proton beam increases linearly with distance from the center
This is expressed mathematically as J(r) = J0 (r/R), where R is the radius of the beam and J0 is the current density at the edge. Determine the value of J0. A) 25 A/m2
B) 6.2 A/m2
C) 12 A/m2
D) 17 A/m2
A
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Which of the following statements about degeneracy pressure is not true?
A) Degeneracy pressure can continue to support an object against gravitational collapse even if the object becomes extremely cold. B) Degeneracy pressure arises from a quantum mechanical effect that we don't notice in our daily lives. C) Black holes form when gravity overcomes neutron degeneracy pressure. D) Degeneracy pressure can arise only from interactions among electrons.
Which of these statements about Hubble's classification scheme for galaxies is false?
A) It represents an evolutionary sequence for galaxies (e.g., type SBa galaxies slowly turn into type SBb). B) Sc galaxies have smaller bulges and more dusty gas than Sa galaxies. C) It includes two broad types of spiral galaxies. D) Low numbered elliptical galaxies are rounder than high numbered elliptical galaxies.
The easiest way to remember which quarks make up a neutron is
A. Neutrons are all about u-three up quarks: uuu. B. The neutron is a real "dud"-a down quark, an up quark, and another down quark: dud. C. A neutron is an inside-out proton: uud. D. Roses are red, violets are blue, neutrons are nosy but do not have u: ddd.
If body P, with a positive charge, is placed in contact with body Q (initially uncharged), what will be the nature of the charge left on Q?
a. must be equal in magnitude to that on P b. must be negative c. must be positive d. must be greater in magnitude than that on P