A solenoid that is $72 \mathrm{~cm}$ long produces a magnetic field of $1.8 \mathrm{~T}$ within its core when it carries a current of $8.1 \mathrm{~A}$. How many turns of wire are contained in this solenoid?

Ultraviolet light is incident normally on the surface of a certain substance. The binding energy of the electrons in this substance is $3.44 \mathrm{eV}$. The incident light has an intensity of $0.055 \mathrm{~W} / \mathrm{m}^2$. The electrons are photoelectrically emitted with a maximum speed of $4.2 \times 10^5 \mathrm{~m} / \mathrm{s}$. How many electrons are emitted from a square centimeter of the surface each second? Assume that the absorption of every photon ejects an electron.

The number of electrons in the outer energy level of a neutral atom of boron (atomic number 5) is

Electrons in $\sigma$-bonding molecular orbitals are most likely to be found in the region between the two bonded atoms. Why does this arrangement favor bonding? In a $\sigma$ antibonding orbital, where are the electrons most likely to be found in relation to the nuclei in a bond?

A toroidal solenoid with 400 turns of wire and a mean radius of $6.0 \mathrm{~cm}$ carries a current of $0.25 \mathrm{~A}$. The relative permeability of the core is 80.What part of the magnetic field is due to atomic currents?

A $2.0 \times 10^{-3} \mathrm{V} / \mathrm{m}$ electric field creates a $3.5 \times 10^{17}$ electrons/s current in a 1.0 -mm-diameter aluminum wire. What are (a) the drift speed and (b) the mean time between collisions for electrons in this wire?

Suppose that wire A and wire B are made of different metals and are subjected to the same electric field in two different circuits. Wire B has 6 times the cross-sectional area, 1.3 times as many mobile electrons per cubic centimeter, and 4 times the mobility of wire A. In the steady state, $2 \times 10^{18}$ electrons enter wire A every second. How many electrons enter wire B every second?

To construct a solenoid, you wrap insulated wire uniformly around a plastic tube $12 \mathrm{~cm}$ in diameter and $55 \mathrm{~cm}$ in length. You would like a $2.0 \mathrm{~A}$ current to produce a $2.5~\mathrm{kG}$ magnetic field inside your solenoid. What is the total length of wire you will need to meet these specifications?

Electrons are accelerated by $6450 \mathrm{~V}$ in an electron microscope. Estimate the maximum possible resolution of the microscope.

Decide whether the statement makes sense (or is clearly true) or does not make sense (or is clearly false). Explain clearly.
Scientists are currently building an infrared telescope designed to observe fusion reactions in the Sun’s core.

A certain superconducting magnet in the form of a solenoid of length 0.500 m can generate a magnetic field of 9.00 T in its core when its coils carry a current of 75.0 A. Find the number of turns in the solenoid.

Give descriptions for the following terms:

a. histone proteins

b. nucleosome core particle

c. CEN sequences

d. G bands

e. euchromatin

f. heterochromatin

g. nucleosome

h. chromosome territory

i. nucleoid

Many writers have paid tribute to Douglass's ideas.

(a) Why do you think his messsage strikes such a chord with Americans?

(b) In what ways does it reflect the core values on which America was founded?

Choose the best answer to given of the following. Explain your reasoning with one or more complete sentences.
Solar energy leaves the core of the Sun in the form of
(a)photons.
(b) rising hot gas.
(c) sound waves.