a uniform electric field E=15 N/C points downwards. A particle with charge q=-0.15 C is placed in the electric field. What is th
1 answer:
Answer:
2.25 N upwards
Explanation:
Answer:
800 N/C to the right
Explanation:
The equation that relates force on a charge, electric field and charge is
where
F is the force acting on the charge
q is the charge
E is the electric field
In this problem, we have
is the electric field
is the charge
Substituting into the formula, we find the force
Concerning the direction:
- The electric field and the force have same directions if the charge is positive
- The electric field and the force have opposite directions if the charge is negative
Here the charge is negative, so the electric field has opposite direction to the force: therefore, it must be upwards.
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Answer:
Explanation:
Case I: They have same charge.
Charge on each sphere = q
Distance between them, d = 14.8 cm = 0.148 m
Repulsive force, F = 0.235 N
Use Coulomb's law in electrostatics
By substituting the values
Thus, the charge on each sphere is .
Case II:
Charge on first sphere = 4q
Charge on second sphere = q
distance between them, d = 0.148 m
Force between them, F = 0.235 N
Use Coulomb's law in electrostatics
By substituting the values
Thus, the charge on second sphere is and the charge on first sphere is
.
1. False
Explanation: it's exactly the opposite. In fact, Lenz's law states that the induced current and the induced emf in a conductor are generated in such a direction that opposes to the change in magnetic flux through the coil. This is summarized by the negative sign in the Faraday's Newmann Lenz law:
where is the emf induced and
is the rate of change of magnetic flux through the coil.
Lenz's law is a consequence of the law of conservation of energy. In fact, we have:
- If the magnetic flux through a coil is increasing, then the induced current has a direction such that the magnetic field generated by the coil is opposite to the direction of the external magnetic field, in order to decrease the total flux
- If the magnetic flux through a coil is decreasing, then the induced current has a direction such that the magnetic field generated by the coil is in the same direction as the external field, in order to increase the total flux
2. False
Explanation: the magnetic flux through a surface is given by
where
B is the magnitude of the magnetic field
A is the surface area
is the angle between the direction of B and the normal vector to the surface
As we see, the magnetic flux depends not only on B and A, but also on the orientation of the coil with respect to the magnetic field.
3. False
Explanation:
- Sound waves are mechanical waves: mechanical waves are waves consisting of oscillations of the particles in a medium. Due to their nature, therefore, mechanical waves can propagate only in the presence of a medium
- Electromagnetic waves are NOT mechanical waves: they consist of oscillations of electric and magnetic fields, in a direction perpendicular to the direction of propagation of the wave. Since em waves are not mechanical waves, they do NOT need a medium to propagate, since they can also travel through a vacuum; therefore the original statement is false.