Answer:
Interchanging the poles of the magnet
Reversing the direction of the applied current
Explanation:
- The working of the electric motor is associated with Fleming's left-hand rule.
- It states that if a current-carrying conductor is placed inside a magnetic field, it experiences a force in the direction perpendicular to the direction of the electric current and magnetic field.
- These three physical quantities are placed in a mutually perpendicular direction.
- So, in order to reverse the direction of force, you have to either change the direction of the current or magnetic field.
Answer:
1.25 m
Explanation:
From the question given above, the following data were obtained:
Force ratio = 2.5
Distance of load from the fulcrum = 0.5 m
Distance of effort =.?
The distance of the effort from the fulcrum can be obtained as illustrated below:
Force ratio = Distance of effort / Distance of load
2.5 = Distance of effort / 0.5
Cross multiply
Distance of effort = 2.5 × 0.5
Distance of effort = 1.25 m
Therefore, the distance of the effort from the fulcrum is 1.25 m
The impulse required to decrease the speed of the boat is equal to the variation of momentum of the boat:
where
m=225 kg is the mass of the boat
is the variation of velocity of the boat
By substituting the numbers into the first equation, we find the impulse:
and the negative sign means the direction of the impulse is against the direction of motion of the boat.
Answer:
The false statement is 'Electric field lines form closed loops'.
Explanation:
- Electric field lines originate from positive end and terminates at negative end,i.e., field lines are inward in direction to the negative charges and outward from the positive charges.
- These lines when close together represents high intensity and when far apart shows low intensity of the field.
- These lines do not intersect, as the tangent drawn on these lines provides us with the field direction and intersection of these lines means two field directions which is not possible.
- These lines unlike magnetic field lines do not form closed loops as they do not turn around but originate at positive end and terminates at negative end which ensures no loop formation.
The energy of a wave is directly proportional to the square of the waves amplitude. Therefore, E = A² where A is the amplitude. This therefore means when the amplitude of a wave is doubled the energy will be quadrupled, when the amplitude is tripled the energy increases by a nine fold and so on.
Thus, in this case if the energy is 4J, then the amplitude will be √4 = 2 .
