What name is used for a high-power variable resistor?

Why do you think it would be more practical to use an electromagnet to move scrap metal than to use a permanent magnet?

Natalija [7]

Answer:

#See solution for details.

Explanation:

-An electromagnet's field can be rapidly changed by just controlling the amount of current. The magnetic strength can be varied over time.

-This way, only a sufficient amount of current will be supplied to meet the needs.

-Unlike the electromagnet, the permanent magnet has a fixed magnetic strength and can only lift a specified weight.

8 0

4 years ago

A 5.0 cm object is 6.0 cm from a convex lens, which has a focal length of 7.0 cm.

Reil [10]

Answer : The distance of the image from the lens is, -42 cm

The height of the image is, 35 cm

Solution :

First we have to calculate the image distance.

Formula used :

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

where,

f = focal length = 7 cm

p = object distance = 6 cm

q = image distance = ?

Now put all the given values in the above formula, we get the distance of the image from the lens.

$\frac{1}{7cm}=\frac{1}{6cm}+\frac{1}{q}$

$q=-42cm$

Therefore, the distance of the image from the lens is, 42 cm and the negative sign indicates that the image is virtual.

Now we have to calculate the height of the image.

Formula used :

$\frac{h}{h'}=\frac{p}{q}$

where,

h = height of object = 5 cm

h' = height of image = ?

Now put all the given values in this formula, we get the height of the image.

$\frac{5cm}{h'}=\frac{6cm}{-42cm}=-35cm$

Therefore, the height of the image is, 35 cm and the negative sign indicates that the image is inverted.

5 0

4 years ago

Read 2 more answers

How many neutrons does this atom have?

labwork [276]

Answer:

6

Explanation:

8 0

3 years ago

Read 2 more answers

A bicyclist makes a trip that consists of three parts, each in the same direction (due north) along a straight road. During the

Advocard [28]

Answer:

a

The total distance traveled is $D = 26760 \ m$

b

The average velocity is $v_{avg} = 6.8 \ m/s$

Explanation:

From the question we are told that

The time taken for first part $t_1 = 22 \ minutes = 22*60 = 1320 \ s$

The speed for the first part is $v_1 = 7.2 \ m/s$

The time taken for second part is $t_2 = 36 \ minutes = 2160 \ s$

The speed for the second part is $v_2 = 5.1 \ m/s$

The time taken for third part is $t_3 = 8 \ minutes = 480 \ s$

The speed for the third part is $v_3 = 13 m/s$

Generally

$distance(D) = velocity * time$

Therefore the total distance traveled is

$D = (v_1 * t_1) + (v_2 * t_2 ) + (v_3 * t_3)$

substituting values

$D = (7.2 * 1320) + (5.1 * 2160) + (13 * 480)$

$D = 26760 \ m$

Generally the average velocity is mathematically represented as

$v_{avg} = \frac{D}{t_{total}}$

Where $t_{total}$ is the total time taken which is mathematically represented as

$t_{total} = 1320 + 2160 + 480$

$t_{total} =3960\ s$

The average velocity is

$v_{avg} = \frac{26760}{3960}$

$v_{avg} = 6.8 \ m/s$

8 0

3 years ago

When the current in a toroidal solenoid is changing at a rate of 0.0240 A/s , the magnitude of the induced emf is 12.4 mV . When

Gemiola [76]

Answer:

The number of turns in the solenoid is 230.

Explanation:

Given that,

Rate of change of current, $\dfrac{dI}{dt}=0.0240\ A/s$

Induced emf, $\epsilon=12.4\ mV=12.4\times 10^{-3}\ V$

Current, I = 1.5 A

Magnetic flux, $\phi=0.00338\ Wb$

The induced emf through the solenoid is given by :

$\epsilon=L\dfrac{dI}{dt}$

or

$L=\dfrac{\epsilon}{(di/dt)}$ ........(1)

The self inductance of the solenoid is given by :

$L=\dfrac{N\phi}{I}$ .........(2)

From equation (1) and (2) we get :

$\dfrac{\epsilon}{(di/dt)}=\dfrac{N\phi}{I}$

N is the number of turns in the solenoid

$N=\dfrac{\epsilon I}{\phi (dI/dt)}$

$N=\dfrac{12.4\times 10^{-3}\times 1.5}{0.00338 \times 0.024}$

N = 229.28 turns

or

N = 230 turns

So, the number of turns in the solenoid is 230. Hence, this is the required solution.

3 0

3 years ago