List two useful properties of current electricity and explain why.

1. Calculate how many electrons you need to get a charge of 1 coulomb.

belka [17]

1) To make a charge of 1 Coulomb, $6.25\cdot 10^{18}$ electrons are needed

2) $3.75\cdot 10^{19}$ electrons are needed to make that current

3) The potential difference is the work done per unit charge by an electric field

4) False, false, true

Explanation:

1)

The charge of one electron is equal to (in magnitude)

$q=1.6\cdot 10^{-19}C$

This is also known as fundamental charge, and it is also indicated with the letter $e$ .

The charge in this problem is

$Q=1 C$

Therefore, in order to calculate how many electrons are in 1 Coulombd of charge, we just divide the total charge by the charge of one electron:

$n=\frac{Q}{q}=\frac{1}{1.6\cdot 10^{-19}}=6.25\cdot 10^{18}$

2)

The current intensity is defined as

$I=\frac{Q}{t}$

where

Q is the charge passing through a given point of a circuit in a time interval t

In this problem, we have

t = 60 s

I = 100 mA = 0.1 A

Therefore, the charge passing through the circuit is

$Q=It=(0.1)(60)=6 C$

We know that the charge of one electron is

$q=1.6\cdot 10^{-19}C$

So the number of electrons is

$n=\frac{Q}{q}=\frac{6}{1.6\cdot 10^{-19}}=3.75\cdot 10^{19}$

3)

The electrical voltage (also called potential difference) can be understood by using the concept of energy and work.

In fact, the work done by an electric field on a charge of magnitude q is

$W=q\Delta V$ (1)

where $\Delta V$ is the potential difference between the initial and final point of motion of the charge. The potential difference is responsible for "pushing" the charge through the circuit (in particular, a positive charge is pushed towards a point of lower potential, while a negative charge is pushed towards a point of higher potential), and when this happens, the electric potential energy of the charge (due to its position in the electric field) is converted into kinetic energy (energy of motion).

So, the potential difference is basically the work done per unit charge by an electric field responsible for the acceleration of a charge, as we can rewrite eq.(1) as

$\Delta V = \frac{W}{q}$

So in this case (where the electric voltage is 5 volts), it means that the work done by this electric field per unit charge is 5 J per Coulomb of charge.

4)

False: Current is the consequence and voltage is the cause. In fact, the voltage (the potential difference between two points in the circuit) is responsible for "pushing" the charges through the circuit, and when the charges start moving, they produce a current.

False: only the battery is a source of voltage. A battery is a device that produces an electromotive force (another name for potential difference), which is responsible for "pushing" the charges through the circuit. A socket, instead, is just a device used to connect another electric device to a voltage supply.

True: an electric current can only flow in a closed circuit. When the circuit is open, in fact, there is a point in the circuit where the flow of charge is interrupted: this means that the current can no longer flow in the circuit, so there is no electric current in an open circuit.

Learn more about current and potential difference:

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#LearnwithBrainly

4 0

4 years ago

A 1100 kg car rounds a curve of radius 68 m banked at an angle of 16 degrees. If the car is traveling at 95 km/h, will a frictio

Mariulka [41]

Answer:

Yes. Towards the center. 8210 N.

Explanation:

Let's first investigate the free-body diagram of the car. The weight of the car has two components: x-direction: towards the center of the curve and y-direction: towards the ground. Note that the ground is not perpendicular to the surface of the Earth is inclined 16 degrees.

In order to find whether the car slides off the road, we should use Newton's Second Law in the direction of x: F = ma.

The net force is equal to $F = \frac{mv^2}{R} = \frac{1100\times (26.3)^2}{68} = 1.1\times 10^4~N$

Note that 95 km/h is equal to 26.3 m/s.

This is the centripetal force and equal to the x-component of the applied force.

$F = mg\sin(16) = 1100(9.8)\sin(16) = 2.97\times10^3$

As can be seen from above, the two forces are not equal to each other. This means that a friction force is needed towards the center of the curve.

The amount of the friction force should be $8.21\times 10^3~N$

Qualitatively, on a banked curve, a car is thrown off the road if it is moving fast. However, if the road has enough friction, then the car stays on the road and move safely. Since the car intends to slide off the road, then the static friction between the tires and the road must be towards the center in order to keep the car in the road.

5 0

4 years ago

When starting a foot race, a 70.0kg sprinter exerts an average force of 650 N backward on the ground for 0.800 s. How far does h

melomori [17]

Answer:

Answer is option b) 2.97m

Explanation:

With the relationship between the force exerted by the runner and the mass that it has, I can determine the acceleration it will have:

F= m × a ⇒ a= (650 kg ×(m/s^2)) / (70kg)= 9.286 (m/s^2)

With the acceleration that prints the force exerted and the time I can determine the distance traveled in the interval:

Distance= (1/2) × a × t^2 = (1/2) × 9.286 (m/s^2) × ((0.8s)^2)= 2.97m

8 0

3 years ago

How many protons are present in an atom

professor190 [17]

Explanation:

The atomic number of an atom represents the number of protons in its nucleus. Therefore, 47 means that there are 47 protons in the atom's nucleus. In this case the atom is that of silver (Ag).

7 0

3 years ago

Shelley is in an elevator that is traveling downward and slowing down at a rate of

liraira [26]

Answer:

N = 648.55[N]

Explanation:

To solve this problem we must use Newton's second law which tells us that the sum of forces on a body is equal to the product of mass by acceleration.

∑F = m*a

where:

∑F = Forces applied [N]

m = mass = 73.2 [kg]

a = acceleration = 0.950 [m/s²]

Let's assume the direction of the upward forces as positive, just as if the movement of the box is upward the acceleration will be positive.

By performing a summation of forces on the vertical axis we obtain all the required forces and other magnitudes to be determined.

$-m*g + N = -m*a\\$

where:

g = gravity acceleration = 9.81 [m/s²]

N = normal force (or weight) measured by the scale = 83.4 [N]

Now replacing:

$-(73.2*9.81)+N=-73.2*0.950\\-718.092+N=-69.54\\N = -69.54+718.092\\N = 648.55[N]$

The acceleration has a negative sign, this means that the elevator is descending at that very moment.

8 0

3 years ago