Biophysics Module 5: Electric and Magnetic Fields of Life

What are the distinct characteristics of electric forces in electro magnetism (2)

Attraction and Repulsion

What does attraction and repulsion depend on

The charge of the body

Just like gravity, electric forces (diminish/ increases) as the __ of separation distance between a pair of interacting charges

Diminish, as the square of separation distance between a pair of interacting charges

Difference between gravity and electromagnetism

Gravity is only attraction, electromagnetism has attraction and repulsion

Scientists used to think that __ and _ were two separate issues before electromagnetism

Electricity and Magnetism

Who helped establish elecctromagnestism?

Maxwell

Magnetism is associated with electricity when __

2 bodies move relative to each other

Maxwells theory encompasses what?

Electricity, Magnetism, and Light

Property of particles with long range interaction depend on what (according to Maxwell)

Charge

Electromagnetic waves are waves like sound waves but the difference is that they are __

Transverse

Electromagnetic waves can travel through a vacuum (y/n)

Yes

Electromagnetic waves travel at what speed through a vacuum

C = 300, 000, 000 m/s

Electromagnetic waves can be __ from one force to another

Transferred

Like sound waves, electromagnetic waves can be ___ or _ after hitting a surface

Reflected or Refracted

Force and Magnetic Field is __ to each other

Perpendicular

In the hand rule what is the thumb, pointer, and middle finger

Thumb = Force
Pointer = Magnetic Field
Middle = Electric Current

Equation of electromagnetic Force

F = qE(electric force) + qv x(cross not times) B(Magnetic Force)

3 Properties of electricity

1. Charge (q)

2. Electric Field (e)

3. Electric Potential or Voltage (A)

What is charge (q)?

Unit of electricity used to describe the size of force an object feels when exposed to other charged objects

Charge is measured in what?

C or Coulombs

What is an electric field

Where the electric force is transfered

Can be thought of as invisible lines

What are electric fields created by

Charged Bodies

What is the electric field expressed in?

N/C, Newtons Per Coulumb

What is Electric Potential/Voltage

Term used to describe the potential energy of electric attraction/repulsion

What is the unit of Electric Potential/Voltage

J/C, Joules per Coulumb

What is coulumbs law formula?

The electromagnetic force of two objects gets weaker or stronger dependent on what 2 factors? What are the relationships of these factors to force?

Charge and Distance

Higher the charge the more repelling/attractive force

The more the distance the less repelling/attractive force

k constant in the coulomb equals what?

9X10^9 N*m²/C²

A proton and an electron have a set charge of __

Proton = 1.6×10^-19

Electron = - 1.6×10^-19

If the force is negative then the objects are (attracting/repulsing)

Attracting

1 Armstrong = How many meters?

1×10^-10

Ohms Law formula

V = I R

Ohms law tells us that the current flowing through a conductor is __ to its resistance

Proportional

Series Circuit

Numerous resistances linked one after another

Parallel circuit

Numerous resistances linked across one another

How many current pathways are in a parallel circuit

More than 1

For series pathways, all the __ are similar and _ is cumulative

Current (because one current), Voltage is cumulative

For parallel pathways, all the __ are similar and _ is cumulative

Voltage are similar, current is cumuative

Humans have __ charge but we still use electricity in biochemical and molecular processes

Neutral

Electric fields line up from the __ to _ side

Positive to Negative

What is electrophysiology

The branch of physiology dealing with electric phenomena associated with living bodies or/and their function

What are the two major points of focus for electrophysiology

CNS and Membrane and ion channels

What is Patch Clamping? (method i electrophysiology)

Uses a micropipette to make contact with the cell, introduces a circuit to measure the membrane potential and analyzes the cell from there

Why is studying ion channels important?

Shows the the membrane potential or separation of charge between 2 environments

Resting membrane potential of Neuron

Has a negative concentration gradient with more potassium inside while theres more sodium outside

Concentration gradient is negative inside the cell so there must be more positive ions outside the cell

What happens when neurotransmitters are released?

Initiates Depolarization causing the neuron to become more positive by allowing for the influx of Sodium ions into the neuron through the opening of sodium channels

Increase in millivolts (MV)

Usage of ion channels can lead you to creating pain medication such as __

Vioxx

Electrocephalograph (EEG)

Records auto electrical activity in the skull and skin, is able to check for seizures, and deep thinking.

Skin voltages have a range of 10-100mV

Electrocardiogram (ECG)

Records the activity of the heart by measuring cutaneous electrical potential across the thorax

This is where the muscles of the heart cells depolarize (contract)

Atrium muscle cells contract in unison due to the electrical signal of __

Sinoatrial node

Defibrilator

Employs a pulse or current to reestablish rhythmic and coherent contraction of heart muscles

Electroshock therapy

Bone growth

Bone growth seems to be faster when the bone has negative charge,

This is associated with the creation of material stress known to produce bone strengthening

For Magnetic Fields, how can the visualization of magnetic force be shown

Arrow heads

Given a magnet with north and south poles, the magnetic field lines of the magnet will be __ on the outside

North to South

Given a magnet with north and south poles, the magnetic field lines of the magnet will be __ on the inside

South to North

How to visualize magnetic fields in real life?

Buying iron fillings and looking where they face

How to measure magnetic force (magnetism)?

Magnetometer

SI units of magnets is __, the force applied to a charge by moving through a magnetic field

Tesla T, or Gauss T = 1×10^4 G

That is the Lorentz Force law ?

Determining the magnetic force (seperate from maxwells law because that was electromagnetic force)

Lorentz force law formulas

F = qV x B

F = qvB sin (theta)

Charge moving across a wire

F = BIL sin (theta)

Right hand rule of magnetism

F = thumb

I (Electric Current)= hand (direction of the wire)

Curling the finger would give you the B (magnetic field)

Amperes Law

Given a current flowing, and given an imaginary loop circling the wire, and given the radius R from the loop to the midpoint.

Then the magnetic field at the edge is weaker than those closer to the current

Magnetic Force which is farther from the current = weaker

Magnetic Flux

Summation of the magnetic field lines given an enclosed area

Si Unit of Magnetic flux is _

Weeber wb

In an enclosed space, the magnetic flux value always equals __

0

Electromagnetic Induction: Galvanometer Experiment

Galvanometer was stationary, magnet was stationary = No deflection

Magnet moved closer = deflection in that direction

Magnet was stationary but it was nearer = no deflection

Magnet was moved further away = deflection

Electromagnetic induction happens due tot he fact that magnetic force is the __

Movement of two objects relative to one another

Faradays 1st Law

EMF (electromagnetic force) changes when magnetic force within a circuit by moving the magnetic field (Property of magnetic induction)

How to move the magnetic field?

• Moving the magnet towards or away from the coil

• Moving the coil into or out of the magnetic field (closer to the field)

• Changing the area of the coil placed in the magnetic field (magnetic flux?)

• Rotating the field relative to the magnet

Faradays 2nd Law

The magnitude of the electromotive force is proportional to the rate of flux linked by the coil

Magnetic flux impacts electromagnetic force

Flux linkage is given by __

Flux * Number of turns in the coil

What is a by product of faradays law?

AC generator

What is the AC generator?

Machine that turns mechanical energy into electrical energy

AC is based on what principle

Electromagnetic Induction

AC has what parts?

Armature, shaft, magnets, slip rings, brushes

Graph of an AC is _

sinusoidal (oscillating)

When the Armature is horizontal with A B going down, flemmings right hand rule directions are

Thumb (motion of conductor) = Up

Index (Magnetic Field) = Right

Middle (Current) = Outward

When the Armature is vertical with A B going down flemings right hand rule directions are

Thumb (motion of conductor) = Down

Index (Magnetic Field) = Right

Middle (Current) = Inward

Electron Spin Resonance

Electrons have a spin which gives it a movement, it acts as a mini bar magnet

Because it has a movement, when it encounters a magnetic field it can spin in 2 ways

Two ways an electron can spin when theres a magnetic field

1. Parallel

2. Anti Parallel

This changing of energy levels in an applied magnetic field is called the __

Zeeman effect

Electron spin resonance or the electron paramagenetic resonance is the __

Spin flip of an electron in a magnetic field

What kind of electrons are affected by electron paramagnetic resonance

Unpaired electrons

What does ESR Spectroscopy do

Using a magnetic field, it can find unpaired electrons due to its changes in spins.

It can not find paired electrons because the two spins cancel each other out

Whether parallel or antiparallel is dependent on

Energy state of the electron

Why is ESR Spectroscopy useful

Can identify free radicals like specific oxygen and nitrogen species

As well as transition metal ions and other paramagnetic species

Concentration of free radicals is normally too low to calculate with magnetism alone, _can help elucidate the size

Uv radiation

Another thing that can help identify characteristics of a molecule with paramagnetic electrons (like a free radical) are __

Spin probes

What is used as a spin probe that was synthesized by us

Nitroxide (has its own unpaired electrons and can interact with other species to tell us information)

Why study free radicals?

Measure of health or disease state

Too much free radicals is instability

Free radicals make more free radicals causing disease and cancer

Nuclear resonance spin spectroscopy

Nuclear magnetic resonance uses large magnets in order measure the interactions between the radio frequency (rf) electromagnetic radiations with the nuclei of molecules placed in a magnetic field.

What do the measurement between the interactions between radio frequency electromagnetic radiation to nuclei help us do

map out the structures, dynamics, reaction state, and environment of the molecules

Map out chemical or protein structure

NMR in Biology

Essentially it maps out protein structures which can be useful when the disease you have missfolds a protein.

Proteins have native states but under specific diseases this can change which would give you different values when you do NMR

Examples of diseases that have missfolded proteins

Type 2 Diabetes, Alzhimers’s, Parkinsons, Cancer, etc.

What is made in Magnetic Resonance Imaging (MRI)

A detailed illustration of organs and tissues, it can show you if you have cancer or tumors or other problems

How does MRI Work?

To create a magnetic resonance image, the body is moved through a strong magnet with a gradient(field inreasing in a direction), radio frequency pulses passing through the body as well

What do radio frequency pulses help check?

Absorbing Protons

MRI is saved for (live/dead) tissue?

Alive

Rationale behind Magnetic Nano Particles

Nano particle delivery is hard

Concept behind Magnetic Nano Particles

There is a drug that is ingested, it is guided by a magnet to reach the desired tumor