Answer:
<em>The force of friction acting on the block has a magnitude of 15 N and acts opposite to the applied force.</em>
Explanation:
<u>Net Force
</u>
The Second Newton's law states that an object acquires acceleration when an unbalanced net force is applied to it.
The acceleration is proportional to the net force and inversely proportional to the mass of the object.
If the object has zero net force, it won't get accelerated and its velocity will remain constant.
The m=2 kg block is being pulled across a horizontal surface by a force of F=15 N and we are told the block moves at a constant velocity. This means the acceleration is zero and therefore the net force is also zero.
Since there is an external force applied to the box, it must have been balanced by the force of friction, thus the force of friction has the same magnitude acting opposite to the applied force.
The force of friction acting on the block has a magnitude of 15 N opposite to the applied force.
Explanation:
Wavelength = speed of light/frequency
Answer is

Answer: the answer is B the lower the resistance,the higher the conductivity
Explanation:
Resistance is inversely proportional to conductivity,the lower the resistance the higher the conductivity,the metal silver has a very low resistance,thus it conductivity is high
Answer:
Magnetic field lines form closed loops around current carrying straight wires.
Explanation:
Magnetic field lines is known to form closed loop (which also serves as a bar magnet) around current carrying conductor in a magnetic field. This direction of the loop around the conductor either clockwise or anticlockwise will determine the direction of current in the conductor.
This directions can be determined using the Maxwell cockscrew or clenched fist rule.
According to clenched fist rule which states if the conductor is grasp with the right hand, the curled finger will point in the direction of the magnetic field and the thumb will point in the direction of the current.
Note that the magnetic field lines around the conductor also behaves like a bar magnet.