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dem82 [27]
3 years ago
11

Electricity costs 10p per unit. How much will it cost Sam to use a 85W laptop and a 60W lamp for an hour?

Physics
1 answer:
Goryan [66]3 years ago
6 0
The standard unit is KW/hr, = 1,000W/hr.
(85 + 60) = 145W.
You need to find its fraction of 1,000W., so (145/1000) = 0.145 KWH.
(0.145 x 10p) = 1.45p. per hr.
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An energy source forces a constant current of 2A to flow through a light bulbfilament for twenty seconds. If 4.6 kJ is given off
QveST [7]

Answer:

The voltage drop across the bulb is 115 V

Explanation:

The voltage drop equation is given by:

V=\frac{\Delta W}{\Delta q}

Where:

ΔW is the total work done (4.6kJ)

Δq is the total charge

We need to use the definition of electric current to find Δq

I=\frac{\Delta q}{\Delta t}

Where:

I is the current (2 A)

Δt is the time (20 s)

2=\frac{\Delta q}{20}

q=40 C

Then, we can put this value of charge in the voltage equation.

V=\frac{4600}{40}=115 V

Therefore, the voltage drop across the bulb is 115 V.

I hope it helps you!

6 0
3 years ago
Two very long uniform lines of charge are parallel and are separated by 0.300 m. each line of charge has charge per unit length
Alenkasestr [34]

linear charge density of system of two line charges is given as

\lambda = 5.20 \muC/m

now as we know that electric field due to a line charge at some distance from it is given by

E = \frac{\lambda}{2\pi \epsilon_0 r}

so here we will first find the electric field of first line charge at the position of other line charge

E = \frac{5.20 * 10^{-6}}{2 \pi * 8.85 * 10^{-12}* 0.300}

E = 312000 N/C

now as we know that

F = qE

here q = charge on the line charge system at which force is required

E = electric field on that system of charge where force is required

now we can find the charge by

q = \lambda * L

q = 5.20 * 10^{-6}* 0.05 = 0.26 * 10^{-6} C

Now using the above formula

F = qE

F = 0.26 * 10^{-6} * 312000

F = 0.0811 N

so force on the part of wire is F = 0.0811 N

8 0
4 years ago
Newton's first law states that objects do not change their motion unless acted upon by a net force. What does the word 'net' mea
ollegr [7]
Answer it is b is the best option to pick A, does that make sense
7 0
4 years ago
A light bulb emitting 1750 Im of luminous flux shines on a book that is 3.0
denis-greek [22]

The illumination of the book is found to be approximately equal to 15 lx.

Option 1.

Explanation:

Luminous flux is the measure of power of the light emitted from a source and illumination is the property of the light to illuminate a given surface when it falls on the surface. So the measure of the region the light flux illuminates the surface is termed as illumination.

As here the luminous flux is given as 1759 lm and the distance of the object which has to be illuminated is placed 3 m away from the source ,the illumination is found to be directly proportional to the luminous flux and inversely proportional to the square of the distance between them

illumination = \frac{Luminous flux}{4\pi d^{2} } \\\\illumination = \frac{1750}{4*3.14*3*3} = 15.48 lx = 15 lx

So, the illumination of the book is found to be approximately equal to 15 lx.

5 0
3 years ago
when a 4.25 kg object is placed on top of a vertical spring the spring compress a distance of 2.62 cm what is the spring force c
Alina [70]

Answer:

425n

Explanation:

4 0
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