1. which of the following is not true about magnetic field lines
a) mag. field lines flow from North to South inside the magnet
b) mag. field lines do not cross
c) mag. field line density is proportional to field strength
d) mag. field is strongest closest to the ends of a bar magnet
is the answer c?
2. Both the electric and gravitational fields:
a) involve mass
b) decrease linearly with distance
c) decrease exponentially with distance
d) contain the same constant
would the answer be d?
1. How would they cross?
2. different constants/r^2
k Q1 Q2/r^2 versus G M1 M2/r^2
see
https://www.google.com/search?q=exponential+field+definition&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&channel=sb#channel=sb&q=exponential+function+definition&revid=132910346&rls=org.mozilla:en-US:official
By the way magnetic field lines usually are draw going from N to S OUTSIDE the magnet.
To find the answer for question 1, you can eliminate the options one by one by understanding the properties of magnetic field lines.
a) Magnetic field lines flow from North to South inside the magnet: This statement is true. Magnetic field lines always flow from the North pole to the South pole inside a magnet.
b) Magnetic field lines do not cross: This statement is true. Magnetic field lines never intersect or cross each other. If they were to cross, it would imply that the magnetic field has two different directions at that point, which is not possible.
c) Magnetic field line density is proportional to field strength: This statement is true. The density or closeness of the magnetic field lines represents the strength of the magnetic field. In regions where the lines are closer together, the field is stronger, and where they are farther apart, the field is weaker.
d) Magnetic field is strongest closest to the ends of a bar magnet: This statement is not true. The magnetic field strength is strongest at the poles of a bar magnet, not just at the ends. The strength decreases as you move away from the poles.
By eliminating the other options, you can conclude that the correct answer for question 1 is not c.
For question 2, let's go through the options:
a) Electric and gravitational fields involve mass: Both electric and gravitational fields do involve mass. In the case of the gravitational field, mass is the source of the field. In the case of the electric field, charges are the source.
b) Electric and gravitational fields decrease linearly with distance: This statement is not true for either field. The electric field follows an inverse square law, which means it decreases with the square of the distance from the source charge. The gravitational field also follows an inverse square law, so it also decreases with the square of the distance from the source mass.
c) Electric and gravitational fields decrease exponentially with distance: This statement is not true for either field. Exponential decrease implies a constant decrease with every unit of distance, which is not the case for electric or gravitational fields.
d) Electric and gravitational fields contain the same constant: This statement is true. Both electric and gravitational fields use the same constant, known as the Coulomb's constant (K) for electric fields and the Universal Gravitational Constant (G) for gravitational fields.
Based on the options given, the correct answer for question 2 is d.