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3 years ago

Electricity cost 10p how much will it cost to use a 85w laptop and a 60w lamp for an hour

Physics

1 answer:

Reil [10]3 years ago

7 0

Answer:

Explanation:

usually electricity is sold in the units of kWh, which I will ASSUME is the case here.

85 W (1 kW/1000W)(1hr)(10 p) = 0.85p

60 W (1 kW/1000W)(1hr)(10 p) = <u>0.60p</u>

together they would cost 1.45 p

which would be rounded down to 1 p

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A toroidal solenoid with mean radius r and cross-sectional area A is wound uniformly with N1 turns. A second toroidal solenoid w

lilavasa [31]

Answer:

Mutual inductance, $M=2.28\times 10^{-5}\ H$

Explanation:

(a) A toroidal solenoid with mean radius r and cross-sectional area A is wound uniformly with N₁ turns. A second thyroidal solenoid with N₂ turns is wound uniformly on top of the first, so that the two solenoids have the same cross-sectional area and mean radius.

Mutual inductance is given by :

$M=\dfrac{\mu_oN_1N_2A}{2\pi r}$

(b) It is given that,

$N_1=550$

$N_2=290$

Radius, r = 10.6 cm = 0.106 m

Area of toroid, $A=0.76\ cm^2=7.6\times 10^{-5}\ m^2$

Mutual inductance, $M=\dfrac{4\pi \times 10^{-7}\times 550\times 290\times 7.6\times 10^{-5}}{2\pi \times 0.106}$

$M=0.0000228\ H$

$M=2.28\times 10^{-5}\ H$

So, the value of mutual inductance of the toroidal solenoid is $2.28\times 10^{-5}\ H$ . Hence, this is the required solution.

8 0

3 years ago

A train whistle is heard at 300 Hz as the train approaches town. The train cuts its speed in half as it nears the station, and t

spin [16.1K]

Answer:

The speed of the train before and after slowing down is 22.12 m/s and 11.06 m/s, respectively.

Explanation:

We can calculate the speed of the train using the Doppler equation:

$f = f_{0}\frac{v + v_{o}}{v - v_{s}}$

Where:

f₀: is the emitted frequency

f: is the frequency heard by the observer

v: is the speed of the sound = 343 m/s

$v_{o}$ : is the speed of the observer = 0 (it is heard in the town)

$v_{s}$ : is the speed of the source =?

The frequency of the train before slowing down is given by:

$f_{b} = f_{0}\frac{v}{v - v_{s_{b}}}$ (1)

Now, the frequency of the train after slowing down is:

$f_{a} = f_{0}\frac{v}{v - v_{s_{a}}}$ (2)

Dividing equation (1) by (2) we have:

$\frac{f_{b}}{f_{a}} = \frac{f_{0}\frac{v}{v - v_{s_{b}}}}{f_{0}\frac{v}{v - v_{s_{a}}}}$

$\frac{f_{b}}{f_{a}} = \frac{v - v_{s_{a}}}{v - v_{s_{b}}}$ (3)

Also, we know that the speed of the train when it is slowing down is half the initial speed so:

$v_{s_{b}} = 2v_{s_{a}}$ (4)

Now, by entering equation (4) into (3) we have:

$\frac{f_{b}}{f_{a}} = \frac{v - v_{s_{a}}}{v - 2v_{s_{a}}}$

$\frac{300 Hz}{290 Hz} = \frac{343 m/s - v_{s_{a}}}{343 m/s - 2v_{s_{a}}}$

By solving the above equation for $v_{s_{a}}$ we can find the speed of the train after slowing down:

$v_{s_{a}} = 11.06 m/s$

Finally, the speed of the train before slowing down is:

$v_{s_{b}} = 11.06 m/s*2 = 22.12 m/s$

Therefore, the speed of the train before and after slowing down is 22.12 m/s and 11.06 m/s, respectively.

I hope it helps you!

7 0

3 years ago

A liquid of density 1200kg/m³ is filled in a beaker upto the depth of 50 cm. calculate the pressure at bottom of the breaker.(g=

sweet-ann [11.9K]

Density=1200kg/m^3=p
Height=50cm=0.5m=h
Acceleration due to Gravity=9.8m/s^2=g

$\boxed{\sf Pressure=pgh}$

$\\ \qquad\quad\sf{:}\dashrightarrow Pressure=1200(0.5)(9.8)$

$\\ \qquad\quad\sf{:}\dashrightarrow Pressure=600(9.8)$

$\\ \qquad\quad\sf{:}\dashrightarrow Pressure=5880Pa$

6 0

3 years ago

Imagine you are holding an apple. how could you increase the potential energy of this apple?

Ray Of Light [21]

If you're holding the apple at your waist, lift it to your mouth.
Potential energy relative to any level is proportional to its height
above that level. Increase that height, and you've increased the
potential energy.

Since energy is conserved ... it never magically appears or
disappears ... you need to tell where that extra energy for the
apple came from.

It's exactly the work you did ... the force of your muscles acting
through the distance you raised the apple ... that became the
additional potential energy that the apple gained.

6 0

3 years ago

A cubical surface surrounds a point charge q . Describe what happens to the total flux through the surface if (c) the surface is

valentina_108 [34]

Answer:

Gauss law states that the electric flux is defined as the electric field multiplied by the area of the surface in a plane perpendicular to the field.

Explanation:

Mathematically,

Φ=Q ϵo

Where;

Q is enclosed charge

ϵo is the permittivity of the free space

According to Gauss law, which states that the electric flux is defined as the electric field multiplied by the area of the surface in a plane perpendicular to the field.

Φ=Q ϵo

Where;

Q is enclosed charge

ϵo is the permittivity of the free space

If the cube is transformed into a sphere the total flux in the electric field remains unchanged or remains the same. This is because the gaussian law does not postulate that electric flux is dependent on the object in a plane. Hence, the transformation of the cube to a sphere does not affect the electric flux generated in the field.

To learn more about how the total flux through a sphere relates to the surface change, click brainly.com/question/4362789

#SPJ4

3 0

1 year ago