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4 years ago

6

Horace has invented a unique pair of reading glasses that have two small light bulbs at the bottom wired in series, so that he c

an see the newspaper when he is reading at night. Each of the bulbs has a resistance of 2.00 , and the system runs off a 3.20-V battery. How much current is drawn by Horace’s reading glasses?

1 answer:

ElenaW [278]4 years ago

3 0

Answer:

The current drawn by Horace’s reading glasses is 0.8 A.

Explanation:

Given that,

Resistance of each bulb, R = 2 ohms

Voltage of the system, V = 3.2 volts

These two bulbs are connected in series. The equivalent resistance will be 2 ohms +2 ohms = 4 ohms

Let I is the current drawn by Horace’s reading glasses. Using Ohm's law to find it such that :

$V=IR\\\\I=\dfrac{V}{R}\\\\I=\dfrac{3.2}{4}\\\\I=0.8\ A$

So, the current drawn by Horace’s reading glasses is 0.8 A.

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Two horizontal pipes have the same diameter, but pipe B is twice as long as pipe A. Water undergoes viscous flow in both pipes,

zheka24 [161]

Answer:

c) 2Q

Explanation:

From the given information:

The pressure inside a pipe can be expressed by using the formula:

$\Delta P = \dfrac{128 \mu L Q}{\pi D^4}$

Since the diameter in both pipes is the same, we can say:

$D = D_A = D_B$

where;

length of the first pipe A $L_A = L$ and the length of the second pipe B $L_B = 2L$

Since the difference in pressure is equivalent in both pipes:

Then:

$\dfrac{128 \mu L_1Q_1}{\pi D_1^4} = \dfrac{128 \mu L_2Q_2}{\pi D_2^4}$

$\dfrac{ L_1Q_1}{D_1^4} = \dfrac{ L_2Q_2}{D_2^4}$

$\dfrac{ LQ_1}{D^4} = \dfrac{ 2LQ}{D^4}$

$\mathbf{Q_1 = 2Q}$

6 0

3 years ago

An object is moving along a straight line, and the uncertainty in its position is 1.90 m.

just olya [345]

Answer:

$2.78\times 10^{-35}\ \text{kg m/s}$

$6.178\times 10^{-34}\ \text{m/s}$

$0.31\times 10^{-4}\ \text{m/s}$

Explanation:

$\Delta x$ = Uncertainty in position = 1.9 m

$\Delta p$ = Uncertainty in momentum

h = Planck's constant = $6.626\times 10^{-34}\ \text{Js}$

m = Mass of object

From Heisenberg's uncertainty principle we know

$\Delta x\Delta p\geq \dfrac{h}{4\pi}\\\Rightarrow \Delta p\geq \dfrac{h}{4\pi\Delta x}\\\Rightarrow \Delta p\geq \dfrac{6.626\times 10^{-34}}{4\pi\times 1.9}\\\Rightarrow \Delta p\geq 2.78\times 10^{-35}\ \text{kg m/s}$

The minimum uncertainty in the momentum of the object is $2.78\times 10^{-35}\ \text{kg m/s}$

Golf ball minimum uncertainty in the momentum of the object

$m=0.045\ \text{kg}$

Uncertainty in velocity is given by

$\Delta p\geq m\Delta v\geq 2.78\times 10^{-35}\\\Rightarrow \Delta v\geq \dfrac{2.78\times 10^{-35}}{m}\\\Rightarrow \Delta v\geq \dfrac{2.78\times 10^{-35}}{0.045}\\\Rightarrow \Delta v\geq 6.178\times 10^{-34}\ \text{m/s}$

The minimum uncertainty in the object's velocity is $6.178\times 10^{-34}\ \text{m/s}$

Electron

$m=9.11\times 10^{-31}\ \text{kg}$

$\Delta v\geq \dfrac{\Delta p}{m}\\\Rightarrow \Delta v\geq \dfrac{2.78\times 10^{-35}}{9.11\times 10^{-31}}\\\Rightarrow \Delta v\geq 0.31\times 10^{-4}\ \text{m/s}$

The minimum uncertainty in the object's velocity is $0.31\times 10^{-4}\ \text{m/s}$ .

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3 years ago

Is direction the length of the route between two points ?

zepelin [54]

Answer:

No distance is the length between two routes

Explanation:

Distance is the length of the route between two points. ... Direction is just as important as distance in describing motion. A vector is a quantity that has both size and direction. It can be used to represent the distance and direction of motion.

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3 years ago

: 1 khối khi lý tưởng nhận được nhiệt lượng 200J, khi đó khí nở ra đẩy pittong bằng 1 công 80J.

Ratling [72]

Answer:

DU = 120 Joules

Explanation:

Given the following data;

Quantity of energy = 200 J

Work = 80 J

To find the change in internal energy;

Mathematically, the change in internal energy of a system is given by the formula;

DU = Q - W

Where;

DU is the change in internal energy.

Q is the quantity of energy.

W is the work done.

Substituting into the formula, we have;

DU = 200 - 80

DU = 120 Joules

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3 years ago

"why might a good electrical conductor also be a good thermal conductor"

zimovet [89]

A good electrical conductor is a material that has a lot of free charges that can easily move across the material, and with a large mean free path.

Now let's assume that one side of the material is at higher temperature than the other side. The charges on the hotter side move faster than the charges on the cooler side, so the faster charges transfer part of their energy to the charges of the cooler side by collisions. The larger the number of free charges (and the larger their mean free path), the faster is this transmission of energy (which is basically transmission of heat), so the larger is the thermal conductivity of the material, so a good electrical conductor is generally also a good thermal conductor.

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3 years ago