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3 years ago

A real image is four times as far from a lens as is theobject.

Physics

1 answer:

saveliy_v [14]3 years ago

3 0

Answer:

1.25 focal lengths

Explanation:

The lens equation states that:

$\frac{1}{f}=\frac{1}{p}+\frac{1}{q}$

where

f is the focal length

p is the object distance

q is the image distance

In this problem, the image is 4 times as far from the lens as is the object: this means that

$q=4p$

If we substitute this into the lens equation and we rearrange it, we get

$\frac{1}{f}=\frac{1}{p}+\frac{1}{4p}=\frac{4+1}{4p}=\frac{5}{4p}\\p=\frac{5}{4}f=1.25 f$

so, the object distance measured in focal lengths is

1.25 focal lenghts

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An uncharged series RC circuit is to be connected across a battery. For each of the following changes, determine whether the tim

slavikrds [6]

a) Increase

b) Unchanged

c) Increase

Explanation:

The charge on a capacitor charging in a RC circuit connected to a battery follows the exponential equation:

$Q(t)=Q_0 (1-e^{-\frac{t}{RC}})$

where

$Q_0 = CV$ is the final charge stored in the capacitor, where C is the capacitance and V is the voltage of the battery

t is the time

R is the resistance of the circuit

The capacitor reaches 90% of its final charge when

$Q(t)=0.90Q_0$

Substituting and re-arranging the equation, we find:

$0.90Q_0 = Q_0(1-e^{-\frac{t}{RC}})\\0.90=1-e^{-\frac{t}{RC}}\\e^{-\frac{t}{RC}}=0.10\\-\frac{t}{RC}=ln(0.10)\\t=-RCln(0.10)=2.30RC$

We see that if we double the RC constant, then $(RC)'=2(RC)$

So the time taken will double as well:

$t'=2.30(RC)'=2.30(2RC)=2(2.30RC)=2t$

So, the answer is "increase"

In this second part, the battery voltage is doubled.

According to the equation written in part a),

$Q_0 =CV$

this means also that the final charge stored on the capacitor will also double.

However, the equation that gives us the time needed for the capacitor to reach 90% of its full charge is

$t=2.30 RC$

We see that this equation does not depend at all on the voltage of the battery.

Therefore, if the battery voltage is doubled, the final charge on the capacitor will double as well, but the time needed for the capacitor to reach 90% of its charge will not change.

So the correct answer is

"unchanged"

In this case, a second resistor is added in series with the original resistor of the circuit.

We know that for two resistors in series, the total resistance of the circuit is given by the sum of the individual resistances:

$R=R_1+R_2$

Since each resistance is a positive value, this means that as we add new resistors, the total resistance of the circuit increases.

Therefore in this problem, if we add a resistor in series to the original circuit, this means that the total resistance of the circuit will increase.

The time taken for the capacitor to reach 90% of its final charge is still

$t=2.30 RC$

As we can see, this time is directly proportional to the resistance of the circuit, R: therefore, if we add a resistor in series, the resistance of the circuit will increase, and therefore this time will increase as well.

So the correct answer is

"increase"

8 0

3 years ago

A active-satellite, one that sends out electromagnetic waves, can be the energy down toward the ocean surface and determine how

Anna71 [15]

Answer: This is called backscatter which refers to the ability of big waves to reflect the energy in order to give back the signal .

Explanation:

What is meant by backscatter?

Backscatter is the process where by the waves or signal is reflected back to the original direction and get scattered in all directions.

Backscatter allows us to receive signal and be able to view all the channels that are connected through the satellite.

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3 years ago

when energy is transferred from one part of a system to another, some of the energy is lost during the transfer and cannot be us

AlladinOne [14]

Sentences A and D describe examples of energy transformation.Heat is produced when a car's tires rub against the pavement and as electricity passes across power wires, they become hotter.

<h3>What is the law of conservation of energy?</h3>

According to the law of conservation of energy, the energy of an isolated system stays unchanged throughout time.it is said to be conserved.

Energy cannot be created nor destroyed and can be transferred from one form to the other form.

The complete question is

"When energy is moved from one component of a system to another, some of the energy is lost and cannot be used as planned.

Which two statements provide examples?

A. Friction between a car's tires and the road produces heat.

B. Sunlight strikes a solar panel, generating electricity.

c. Stereo speakers emit a sound when powered by electrical energy,

D. Wind moves a turbine, generating electricity.

I E. Power lines heat up as electricity flows through them."

Some of the energy wasted during the movement of energy from one section of a system to another is heat is produced by friction between a car's tires and the road and as electricity passes via power lines, they heat up.

Hence, sentences A and D describe examples of energy transformation.

To learn more about the law of conservation of energy refer to the link;

brainly.com/question/2137260

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Which variety of moth, C or Y, is more likely to be killed by insect eating birds?

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