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My name is Ann [436]

2 years ago

11

a person is sitting on the last bench can see clearly see things written on book but cannot see them distinctly on board. what t

ypes of lens is this concave or convex

1 answer:

marysya [2.9K]2 years ago

7 0

Answer:

I think concave

Explanation:

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Explain, in complete sentences, Issac Newton's Laws Of Motion. Explain how each law is applied in the real world

LUCKY_DIMON [66]

Everyone gets so be safe with every law there is

5 0

3 years ago

Read 2 more answers

Name 3 examples of the Doppler Effect

sveta [45]

Answer:

The drop in pitch of ambulance sirens as they pass by and the shift in red light are common examples of the Doppler Effect.

...

It is used in:

Sirens.

Astronomy.

Radars.

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Flow management.

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(It is so much but you can select three of them and write it)

5 0

3 years ago

Please please help me :)

mrs_skeptik [129]

Answer:

Explanation:

2) From F=ma

Force =15×40=600N or kgm/s2

3)From the same equation making acceleration the subject of the formula will give

a=f÷m

=24÷4=6m/s2

4)m=f÷a

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4 0

3 years ago

A wire of resistance 7 ohms and length 2.8 m is bent into a circle and is concentric with a solenoid in which the magnetic flux

Serggg [28]

Answer:

The emf, electric field and the current in the wire are 10 V, 3.57 V/m and 1.43 A.

Explanation:

Given that,

Resistance = 7 ohms

Length = 2.8 m

Time t =0.2

We need to calculate the change in magnetic flux

Using formula of induced emf

$\epsilon=\dfrac{d\phi}{dt}$

Put the value into the formula

$\epsilon=\dfrac{6-4}{0.2}$

$\epsilon=10\ V$

We need to calculate the electric field in the wire

Using formula of electric field

$E=\dfrac{V}{l}$

$E=\dfrac{10}{2.8}$

$E=3.57\ V/m$

We need to calculate the current in the wire,

Using formula of ohm's law

$V=IR$

$I=\dfrac{V}{R}$

Put the value into the formula

$I=\dfrac{10}{7}$

$I=1.43\ A$

Hence, The emf, electric field and the current in the wire are 10 V, 3.57 V/m and 1.43 A.

7 0

3 years ago

In the United States, household electric power is provided at a frequency of 60 HzHz, so electromagnetic radiation at that frequ

grigory [225]

Answer:

the maximum intensity of an electromagnetic wave at the given frequency is 45 kW/m²

Explanation:

Given the data in the question;

To determine the maximum intensity of an electromagnetic wave, we use the formula;

$I$ = $\frac{1}{2}$ ε₀cE $_{max$ ²

where ε₀ is permittivity of free space ( 8.85 × 10⁻¹² C²/N.m² )

c is the speed of light ( 3 × 10⁸ m/s )

E $_{max$ is the maximum magnitude of the electric field

first we calculate the maximum magnitude of the electric field ( E $_{max$ )

E $_{max$ = 350/f kV/m

given that frequency of 60 Hz, we substitute

E $_{max$ = 350/60 kV/m

E $_{max$ = 5.83333 kV/m

E $_{max$ = 5.83333 kV/m × ( $\frac{1000 V/m}{1 kV/m}$ )

E $_{max$ = 5833.33 N/C

so we substitute all our values into the formula for intensity of an electromagnetic wave;

$I$ = $\frac{1}{2}$ ε₀cE $_{max$ ²

$I$ = $\frac{1}{2}$ × ( 8.85 × 10⁻¹² C²/N.m² ) × ( 3 × 10⁸ m/s ) × ( 5833.33 N/C )²

$I$ = 45 × 10³ W/m²

$I$ = 45 × 10³ W/m² × ( $\frac{1 kW/m^2}{10^3W/m^2}$ )

$I$ = 45 kW/m²

Therefore, the maximum intensity of an electromagnetic wave at the given frequency is 45 kW/m²

7 0

2 years ago