Why does a pencil in a glass container filled with water appear to be bent?

2 answers:

4 0

The phenomenon is called "refraction". It's the process of
light waves bending toward a different direction when they
cross a boundary between different media ... in this case,
from water into air.

Your brain doesn't know that the light waves bent toward a
new direction when they came out of the water into the air,
so your brain locates the bottom half of the pencil just like it
ALWAYS does ... in the direction the light waves are coming FROM.

Anit [1.1K]4 years ago

3 0

The answer is B.refraction. when light refract under water the pencil can appear to bent

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If a voltmeter has a less than ideal resistance, say 1 MΩ, and is used to measure the voltage across a resistor of a comparable

Naddik [55]

Answer:

As the difference between the resistance of voltmeter and the resistance being measured gets reduced the error in the reading of the voltmeter gets increased.

Explanation:

An ideal voltmeter has infinite parallel resistance and because of this it doesn't draw any current from the circuit of measurement which means it will measure the exact voltage across the elements.

But practically speaking, a real voltmeter doesn't has infinite resistance therefore, all the practical voltmeters face loading effect to some extent.

As the difference between the resistance of voltmeter and the resistance being measured gets reduced the error in the reading of the voltmeter gets increased. This is why we want to have a greater value of voltmeter resistance, ideally infinite so that the corresponding error is minimized.

Lets consider the given scenario,

A voltmeter has 1 MΩ parallel resistance and the resistance of of measuring element is 500 kΩ or 0.5 MΩ

lets suppose the supplied voltage is 1 V.

First lets assume that the voltmeter is ideal and it has infinite resistance, so in this case voltmeter will measure a voltage of 1 V across the 0.5 MΩ resistor.

Now consider the loading effect, when we connect the voltmeter across the 0.5 MΩ resistor they both become parallel so the resistance is

R = (1*0.5)/(1+0.5)

R = 0.33 MΩ

As you can see the voltmeter will see a reduced resistance and the corresponding voltage also reduces because resistance and voltage are directly proportional.

Therefore, it is preferred to have a very high parallel resistance of the voltmeter.

8 0

3 years ago

Find the wavelength (in nm) of a 2.52 eV photon. a. 492.34127 nm.b. 585.88611 nm.c. 541.5754 nm.d. 418.49008 nm.

elena-14-01-66 [18.8K]

Answer:

The correct option is (a).

Explanation:

Given that,

The energy of photon, E = 2.52 eV

We need to find the wavelength of the photon in nm. The formula for the energy of a photon is given by :

$E=\dfrac{hc}{\lambda}\\\\\lambda=\dfrac{hc}{E}\\\\\lambda=\dfrac{6.63\times 10^{-34}\times 3\times 10^8}{2.52\times 1.6\times 10^{-19}}\\\\=4.93\times 10^{-7}\ m\\\\=493\ nm$