<u>**Answer:**</u>

**"Where friction or rubbing results in the transfer of electrons between particles, objects can become negatively or positively charged."**

<u>**Explanation:**</u>

**The motion resistance of one moving object with respect to another is called as "Friction"**. It isn't a basic force, like gravity or electromagnetism. Alternatively, scientists believe it is the product of the electromagnetic attraction in two touching surfaces between charged particles.

The friction have formula:

**Friction force (****<em>f </em>****) = coefficient of friction × normal force (N)
**

For an instances when one ride a bicycle, an example of rolling friction is the contact between the wheel and the way.

**Answer:**

**a)** When **R** is very small **R << r**, therefore the term **R+ r** will equal **r** and the current becomes

**b) **When **R** is very large, **R >> r, **therefore the term **R+ r** will equal **R** and the current becomes

**Explanation:**

<u>**Solution :**</u>

**(a)** We want to get the consumed power P when R is very small. The resistor in the circuit consumed the power from this battery. In this case, the current I is leaving the source at the higher-potential terminal and the energy is being delivered to the external circuit where the rate (power) of this transfer is given by equation in the next form

P=∈*I-I^2*r **(1)**

Where the term ∈*I is the rate at which work is done by the battery and the term I^2*r is the rate at which electrical energy is dissipated in the internal resistance of the battery. The current in the circuit depends on the internal resistance r and we can apply equation to get the current by

I=∈/R+r **(2)**

When R is very small R << r, therefore the term R+ r will equal r and the current becomes

I= ∈/r

Now let us plug this expression of I into equation (1) to get the consumed power

P=∈*I-I^2*r

=I(∈-I*r)

=0

The consumed power when R is very small is** zero **

**(b) **When **R** is very large, **R** >> r, therefore the term **R+ r** will equal **R** and the current becomes

I=∈/R

The dissipated power due toll could be calculated by using equation.

P=I^2*r **(3)**

Now let us plug the expression of I into** equation (3)** to get **P**

P=I^2*R=(∈/R)^2*R

**=∈^2/R**

**Answer:**

groups on and two have the highest reactivity

**Explanation:**

the farther you move to the right the more reactive the elements get