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# Tag Archives: proton

## Neutrons, Neutrons, Neutrons

I understand that  in large elements which contain many protons, there exist too many neutrons to extend the strength of strong nuclear force and to overcome the electromagnetic repulsion force of protons. Such elements are stable in this way. But, I read that element with too many neutrons are also unstable. WHY ?  What I know is that too many neutrons can’t enlarge the electromagnetic repulsion force and can increase the strong nuclear force, so they even make the nucleus more stable . What’s wrong with me ? Please!

## Why protons and electrons do not collapse and cancel?

According to Physics opposite charges always attract But in an atom the distance between nucleus and electrons are small then why electrons didnt combined with protons? protons and electrons have opposite charges.But why they didnt combined each other?

“Good question,, both sub-atomic particle have certain mass and energy,, we also know that it,, there is electrons revolved an nucleus and their corresponding energy level,, so that it don’t care their charges.. only arrange respect that energy,,,,

the minimum distance between nucleus and orbital electron have minimum energy, as well as large distance it as more energy.”

## How protons became closer during Big bang process?

I know that strong nuclear force is a short-ranged force. So, I would like to know how protons became closer during Big bang process. Is it because of very high temperature and pressure during this ?

(thatoekhant)

In nuclear fusion the nucleons (protons and neutrons come closer because of their high energies. When they come closer to each other in the order of distances of fermi (10^-15 m) nuclear force – the strongest force in nature, comes into play

… Awaiting responses

## Work done in accelerating a proton

The mass of a proton is 1840 times that of an electron. it is accelerated to a potential difference of 1kV. find the amount of work done in process. (Ujjwal Sharma asked)

The work done = the KE acquired = eV=1.6 x 10-19 x 1000 = 1.6 x 10-16 J

## How atoms are formed? – Neeraj Asks

Neeraj asks: ”We have read that atoms can neither been created nor been destroyed!
I want to know from where atoms came in existence,if they can not been created,also atom contain electron and proton which are negatively and positively charged,i want to know from where these charge came?”

## de Broglie Wavelength

Alpha particle and a proton are accelerated from rest by the same potential. Find the ratio of their de- broglie wavelength

Charge of alpha particle = 2e

Mass of alpha particle = 4 u

Charge of proton = e

mass of proton = u

The energy acquired by proton when accelerated through a pd of V,

E=eV

The momentum acquired by proton=${\sqrt{2ueV}}$

The de Broglie wavelength is given by $\lambda =\frac{h}{mv}$

Therefore, de Broglie wavelength of Proton, $\lambda _{proton}=\frac{h}{\sqrt{2ueV}}$

Similarly,$\lambda _{alpha}=\frac{h}{\sqrt{2\times 4u\times 2e\times V}}$

$\frac{\lambda _{alpha}}{\lambda _{proton}}=\frac{\sqrt{2ueV}}{\sqrt{2\times 4u\times 2e\times V}}=\frac{1}{2\sqrt{2}}$

## Collection of Problems received from Class 12 Physics

These problems were posted by Geena. Hope that we will be able to post the answers to these questions soon; each in a separate post. By the time visitors can attempt to post their answers as comments to this post. (Only selected posts will be published)

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1. A series battery of 10 lead accumulators each of emf 2 V and internal resistance 0.25 ohm is charged by a 220 V D.C. mains to limit the charging current a resistance of 47.5 ohm is used in series in the charging circuit. What is a) the power supplied by the mains and b) power dissipated as heat? Account for the difference of powers is (a) and (b).
2. A potentiometer wire has a length L and a resistance Ro. It is connected to a battery and
a resistance combination as shown. Obtain an expression for the potential drop per unit length of this potentiometer wire. What is the maximum emf of a ‘test cell’ for which one can get a ‘balance point’ on this potentiometer wire? What precaution should one take, while connecting this ‘test cell’ , in the circuit?
3. A cell, of emf 4 V and .internal resistance 0.5 Ω, is connected across a load of resistance (i) 7.5 Ω, (ii) 11.5 Ω. Calculate (i) the ratio of the differences in the emf of the cell and the potential drop across the load, and (ii) the ratio of the currents in the two cases.
4. In the figure shown, calculate the total flux of the electrostatic field through the spheres S1 and S2 The wire, AB, shown here, has a linear charge density, λ given by λ = kx where x is the distance measured along the wire, from the end A.
5. A straight wire, of length L, carrying a current I, stays suspended horizontally in mid air in a region where there is a uniform magnetic field B . The linear mass density of the wire is λ. Obtain the magnitude and direction of this magnetic field.
6. Two cells of same emf E, but different internal resistance rl and r2 are connected to an external resistance R as shown. in the figure. The voltmeter V reads zero. Obtain an expression for R in terms of rl and r2. Calculate the voltage across the cell of internal resistance r2. (Assume that the voltmeter V is of infinite resistance).
7. A galvanometer with a coil of resistance 120 ohm shows full scale deflection for a current of 2.5 mA How will you convert the galvanometer into an ammeter of range 0 to 7.5 A ? Determine the net resistance of the ammeter. When an ammeter is put in a circuit, does it read slightly less or more than the actual current in the original circuit? Justify your answer.
8. Figure shows a bar magnet M falling under gravity through an air cored coil C. Plot a graph
showing the variation of induced e.m.f (E) with time (t). What does the area enclosed by the
E – t curve depict ?
9. The electron in the hydrogen atom circles around the proton with a speed of 2.18 x 106 m/s in an orbit of radius 5.13 x 10 -11 m. What magnetic field does it produce at the centre?
10. A proton moves with a speed of 7.45 x 105 m/s directly towards a free proton originally at rest. Find the distance of the closest approach for the two protons. (Given: mass of proton = 1.67 x 10–27 kg and e = 1.6 x 10 –19 C)
11. Figure (a), (b) and (c) show three a.c. circuits in which equal currents are flowing. If the frequency of emf be increased, how will the current be affected in these circuits? Give reason for your answer.

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