Ask question

Ask question

All categories

3 years ago

8

A parallel plate capacitor has two plates has a separation d. If I charge it with a +Q and a ????Q on the two plates, respective

ly, what is the electrostatic energy? What is it if I move to 1/2 d?

1 answer:

EleoNora [17]3 years ago

5 0

Answer:

Explanation:

Electric energy per unit volume

= (1 / 2) x ε₀ E²

Total energy

= energy per unit volume x volume

= (1 / 2) x ε₀ E² x A d , A is plate area

= (1 / 2A) x (ε₀ (σ/ε₀)² x A² d) [ E is electric field ]

(1 / 2A) x (ε₀ (σA/ε₀)² X d)

(1 / 2A) x (ε₀ (Q/ε₀)² X d

= (1 / 2A) x (Q²/ε₀) x d

So total energy is proportional to d , distance between plates

if d is changed to d/2

total energy also becomes half.

(1 / 2A) x (Q²/ε₀) x d / 2

(1 / 4A) x (Q²/ε₀) x d

=

You might be interested in

Suzy drops a rock from the roof of her house. Mary sees the rock pass her 2.9 m tall window in 0.134 sec. From how high above th

timama [110]

Answer:

Explanation:

Given

length of window $h=2.9\ m$

time Frame for which rock can be seen is $\Delta t=0.134\ s$

Suppose h is height above which rock is dropped

Time taken to cover $h+2.9 is t_1$

so using equation of motion

$y=ut+\frac{1}{2}at^2$

where y=displacement

u=initial velocity

a=acceleration

t=time

time taken to travel h is

$h=0+0.5\times g\times (t_2)^2---2$

Subtract 1 and 2 we get

$2.9=0.5g(t_1^2-t_2^2)$

$5.8=g(t_1+t_2)(t_1-t_2))$

and from equation $t_1-t_2=0.134\ s$

so $t_1+t_2=\frac{5.8}{9.8\times 0.134}$

$t_1+t_2=4.416\ s$

and $t_1=t_2+\Delta t$

so $t_2+\Delta t+t_2=4.416$

$2t_2+0.134=4.416$

$t_2=0.5\times 4.282$

$t_2=2.141\ s$

substitute the value of $t_2$ in equation 2

$h=0.5\times 9.8\times (2.141)^2$

$h=22.46\ m$

8 0

3 years ago

If you walk 30 meters forwards, and then turn around and walk 25 meters backwards, what is the distance that you walked? What di

xeze [42]

Given :

Walk in forward direction is 30 m .

Walk in backward direction is 25 m .

To Find :

The distance and displacement .

Solution :

We know , distance is total distance covered and displacement is distance between final and initial position .

So , distance travelled is :

D = 30 + 25 m = 55 m .

Now , we first move 30 m in forward direction and then 25 m in backward direction .

So , displacement is :

D = 30 - 25 m = 5 m .

Therefore , distance and displacement covered is 55 m and 5 m respectively .

Hence , this is the required solution .

5 0

3 years ago

Zoe finds that the temperature of a substance is 12 degrees Celsius. What does this tell Zoe about the substance?

maks197457 [2]

Given the temperature, we can tell if the substance is cold or not relative to the reference temperature. For example, compared to the substance having a temperature of 15 degrees C, the substance is colder and it is hotter from the substance of temperature lesser than 12 degrees C.

5 0

3 years ago

Read 2 more answers

Joan stirred a pot of hot soup with a metal spoon. after a minute or two, the handle of the spoon became too hot to hold. what k

natima [27]

When the metal spoon comes in contact with the hot soup, heat transfer from hot soup to the spoon because of difference in temperature of the two. The kind of heat transfer represented here is conduction. In conduction, heat is transferred from a region of higher temperature to a region of lower temperature when there is a physical contact between the two.

4 0

3 years ago

A guitar string with a length of 80.0 cm is plucked. The speed of a wave in the string is 400 m/sec. Calculate the frequency of

Sholpan [36]

Answer:

The first harmonic is: 250Hz, second harmonic 500Hz, third harmonic 750Hz.

Explanation:

Use the frequency f, speed v, and wavelentgh L relationship:

$v = f\cdot L\implies f = \frac{v}{L}$

We are given the speed v=400 m/s. The base wavelength on a string of length 80cm is twice the length of the string (a "half wave" along the full length of the string), so:

$f = \frac{400\frac{m}{s}}{2\cdot0.8 m}= 250\frac{1}{s}=250 Hz$

The fundamental frequency (first harmonic) is 250 Hz

The second harmonic is produced by one full wave across the string (adding one node in the middle), so L=80cm in this case, therefore the second harmonic frequency is: f2 = 2*250=500Hz

the third harmonic add another node (and a half wave) to the pattern and the wavelength will be 2/3 of 80cm, so f3=3*250Hz = 750Hz

8 0

3 years ago