In a television tube the picture is formed by streams of electrons hitting the screen. The current is 20 mA. How much electric charge hits the screen in 30 minutes?​

Quantity of charge = 36 Coulombs.

Explanation:

Given the following data;

Current = 20 mA = 20/1000 = 0.02 Amperes

Time, t = 30 minutes to seconds = 30 * 60 = 1800 seconds

To find the quantity of charge;

Quantity of charge = current * time

Quantity of charge = 0.02 * 1800

Quantity of charge = 36 Coulombs.

answer: electrons

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

                                              ⇒      

here   k is the proportionality constant whose value is 1.

                                                            [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.