A single atom of an element has 11 protons ,11 electrons.12 neutrons . Which element is it ?

After a check up, a person now has a far point of 100 cm, but with good near point vision. He needs to wear a new pair of correc

lakkis [162]

Answer:

so his far point according to this pair of glass is 200 cm

Explanation:

power of old pair of corrective glasses is given as

$P = -0.5 dioptre$

now we have

$f = \frac{1}{P}$

$f = -2 m$

$f = -200 cm$

now we know that for normal vision the maximum distance of vision is for infinite distance

so by lens formula we have

$\frac{1}{d_i} + \frac{1}{d_o} = \frac{1}{f}$

$\frac{1}{d_i} + 0 = \frac{1}{200}$

$d_i = 200 cm$

so his far point according to this pair of glass is 200 cm

7 0

3 years ago

A 60-W light bulb runs on 120 V and draws 0.50 A of current when running

Pavlova-9 [17]

Answer:

3600 J

Explanation:

According to given question

P(rated)=60w

V= 120

I =0.50 A

t=600 second

Now,

Energy can be calculated as :

$E= VI*t$

Where,

V is voltage

I is current

t is time in second

Now,

Putting the all value in above equation E

So,

$E=120*0.5*600\\E=36000 J$

Therefore, 36000 J energy use up by light bulb

8 0

3 years ago

A positive and a negative charge are initially 4 cm apart. When they are moved closer together so that they are now only 1 cm ap

GarryVolchara [31]

Answer:

$\boxed{\tt(b) \: 4 \: times \: larger \: than \: before}$

8 0

3 years ago

Batteries are rated in terms of ampere-hours (A·h). For example, a battery that can produce a current of 2.00 A for 3.00 h is ra

Reptile [31]

(a) 423 J

The power of the battery is the ratio between the total energy stored (E) and the time elapsed (t):

$P=\frac{E}{t}$

However, the power is also the product of the voltage (V) and the current (I):

$P=VI$

Linking the two equations together,

$\frac{E}{t}=VI\\E=VIt$

Since we know:

V = 9.0 V

$I \cdot t = 47.0 A\cdot h$

We can calculate the total energy:

$E=(9.0 V)(47 A \cdot h)=423 J$

(b) $7.79\cdot 10^{-6}$ dollars

The battery has a total energy of E = 423 J. (2)

1 Watt (W) is equal to 1 Joule (J) per second (s):

$1 W = \frac{1 J}{1 s}$

so 1 kW corresponds to 1000 J/s:

$1 kW = \frac{1000 J}{1 s}$

Multiplying both side by 1 hour (1 h):

$1 kW \cdot h = \frac{1000 J}{1 s} 1 h$

and $1 h = 3600 s$ , so

$1 kWh = \frac{1000 J}{1 s}\cdot 3600 s =3.6\cdot 10^6 J$

So we find the conversion between kWh and Joules. So now we can convert the energy from Joules (2) into kWh:

$1 kWh = 3.6\cdot 10^6 J = x : 423 J\\x=\frac{1 kWh \cdot 423 J}{3.6\cdot 10^6 J}=1.18\cdot 10^{-4}kWh$

And since the cost is $0.0660 per kilowatt-hour, the total cost will be

$C=$0.0660\cdot 1.18\cdot 10^{-4} kWh=7.79\cdot 10^{-6}$ dollars

6 0

4 years ago

If a car rolls gently off a vertical cliff, how long does it take to reach 90km/hr.

Naddik [55]

90 km/h : 3.6 = 25 m/s. If you know that on earth g = 9.81 m/s^2, then all you have to do is divide the speed by g. 25/9.81 = 2.548 seconds

At least, if by 'gently rolls off a vertical cliff' means that your starting velocity equals zero.

5 0

3 years ago