1) a) attract
The magnetic force between two magnetic poles is attractive for two unlike poles and repulsive for two like poles. Therefore we have:
1- For two north poles, the force between them is repulsive
2- For two south poles, the force between them is repulsive
3- For a north pole and a south pole, the force between them is attractive
In this problem, we are in the situation described in 3), so the force between the poles is attractive.
2) a) motion of electrons
While electric fields are produced by static electric charges, magnetic fields are produced by charges in motion (currents). In particular, a current in a wire (where a current is simply the motion of electrons inside the wire) produces a magnetic field whose intensity is
where
I is the current in the wire
r is the radial distance from the wire
And the direction of the field lines are such that the field form concentric circles around the wire.
Answer:
Swimmer A
Explanation:
The time required for a swimmer to cross a river is equal to the width of the river which is divided by the magnitude of the component of the velocity which is parallel to the width of the river.
In the given context, all the three swimmers A, B and C swims in a different angle relative to the direction of the flow of river. The swimmer A swims straight at a direction perpendicular to the direction of current of the river across the width of the river, so A will have the largest velocity component which is parallel to the width of the river. So the time taken by swimmer A will be the least to cross the river.
Answer:
Number of photons emit per second = 1.9 × 10²⁹ (Approx)
Explanation:
Given:
Frequency = 91.5 MHz
Power = 11.5 Kw = 11,500 J/s
Find:
Number of photons emit per second
Computation:
Total energy with frequency (E) = hf
Total energy with frequency (E) = 6.626×10⁻³⁴ × 91.5×10⁶
Total energy with frequency (E) = 6.06×10⁻²⁶ J
Number of photons emit per second = 11,500 / 6.06×10⁻²⁶
Number of photons emit per second = 1897.689 × 10²⁶
Number of photons emit per second = 1.9 × 10²⁹ (Approx)
Answer:
Q = 29.4 x 10⁻⁹ C.
Explanation:
Electric field due to a charge Q at distance d is given by coulomb law as follows
Electric field
E = k Q /d²
where for air k which is a constant is 9 x 10⁹
Given E = 32.08 , d = 2.84 m
Putting these values in the relation above, we have
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Q = 29.4 x 10⁻⁹ C.
Thermal energy Thermal energy <span>Thermal energy</span>