science and inventions
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- Strip electrons from an atom and the atom becomes
- positive ion
- To say that electric charge is conserved means that no case has ever been found where the
- net charge has been created or destroyed
- A conductor differs from an insulator in that a conductor
- who knows
- Charge carriers in a metal are electrons rather than protons because electrons are
- loosely bound
- Electrons are made to flow in a wire when there is
- a potential difference across its ends
- A wire that carries an electric current
- may be electrically charged
- Charge flows in a
- closed circuit
- A wire carrying a current is normally charged
- not at all
- The primary source of electrons in an ordinary electrical circuit is
- the electrical circuit itself
- Alternating current is normally produced by a
- generator
- In a simple circuit containing a bulb, energy is given to the moving charges by
- a generator
- A positive ion has more
- protons than electrons
- Moving electric charges will interact with
- an electric field or a magnetic field
- Like kinds of magnetic poles repel while unlike kinds of magnetic poles
- attract
- An iron nail is more strongly attracted to the
- north or south pole - no difference
- Magnetic field lines about a current-carrying wire
- circle the wire in closed loops
- If we think of the Earth as a magnet, its north (-seeking) pole is nearest
- Australia
- Which pole of a compass needle points to a south pole of a magnet?
- north pole
- Outside a magnet, magnetic field lines are conventionally drawn from
- north to south
- When a bar magnet is broken in two, each half is
- as magnetic as the original magnet
- Thrust a magnet into a coil of wire and the coil
- has a current in it
- In an electrically neutral atom the number of protons in the nucleus is equal to the number of
- electrons that surround the nucleus
- To say that electric charge is quantized is to say that the charge on an object
- is a whole-number multiple of the charge of one electron
- To say that electric charge is conserved is to say that electric charge
- can neither be created nor destroyed
- Rub electrons from your hair with a comb and the comb becomes
- negatively charged
- An electron and a proton
- attract each other
- If you comb your hair and the comb becomes positively charged, then your hair become
- negatively charged
- A balloon will stick to a wooden wall if the balloon is charged
- either positively or negatively
- The magnetic field strength inside a current-carrying coil will be greater if the coil encloses a
- rod of iron
- A device that transforms electrical energy to mechanical energy is a
- motor
- When a bar magnet is thrust into a coil of copper wire, the coil tends to
- repel the magnet as it enters
- A device that transforms mechanical energy into electrical energy is a
- a generator
- Electromagnetic induction occurs in a coil when there is a change in
- magnetic field intensity in the coil
- When Rutherford had a stream of alpha particles hit a gold foil, most of the particles
- went almost straight through
- X-rays are similar to
- gamma rays
- Which radiation has no electric charge associated with it?
- gamma rays
- Both X-rays and gamma rays are emitted from
- different parts of the atom
- The sources of Xrays and gamma rays, respectively, are
- electron clouds and the atomic nucleus
- A nucleon is either
- a proton or a neutron
- Once an alpha particle is outside the nucleus it is
- electrostatically repelled
- An atom with an imbalance of electrons to protons is
- an ion
- Deuterium and tritium are both
- forms of hydrogen and isotopes of the same element
- The atomic number of an element is the same as the number of its
- protons
- Different isotopes of an element have different numbers of
- neutrons
- Most alpha particles fired at a gold foil passthrough undeflected because the
- atoms of gold, like any other atoms, are mostly empty space
- Generally speaking, the larger a nucleus is, the greater its
- instability
- The half life of an isotope is one day. At the end of three days, how much of the isotope remains?
- one eighth
- According to Niels Bohr, an electron in an excited state could give off
- several photons in a series of transitions to the ground state
- The Bohr model of the atom is similar to
- a miniature solar system
- We now consider the Bohr model of the atom to be
- defective and oversimplified but useful
- Compared to the average diameter of a hydrogen atom, the average diameter of a helium atom is
- smaller
- Heavy atoms are not appreciably larger in size than light atoms because the nuclei of heavy atoms have more
- electric charge
- What is it that electrons have that protons always have in equal magnitude?
- charge
- X-rays may be regarded as
- high frequency radio waves
- In the Heliocentric World System
- the sun is at the center of the universe and planets revolve around it
- According to Newton, gravitation is
- a universal attractive force
- According to the Big Bang Model,
- the universe is expanding
- Dark Energy is thought to be
- the cause of the acceleration of the universe
- Which of these electromagentic waves has the shortest wavelength?
- X-rays
- When visible light is incident upon clear glass, atoms in the glass
- are forced into vibration
- Infrared waves are often called heat waves because they
- induce resonance in molecules and increase internal energy in a substance
- Sunburns are produced by
- ultraviolet light
- Which of the following can not travel a vacuum?
- a sound wave
- A pair of sunglasses and a pair of reading glasses are left in the sunlight. The hotter glasses would be the
- sunglasses
- The color of an opaque object is the same as the light that is
- reflected
- What color light is transmitted by a piece of blue glass?
- blue
- Complimentary colors are two colors that
- produce white light when added together
- Different colors of light correspond to different light
- frequencies
- A mixture of cyan and yellow pigments appears
- green
- The sky is blue because air molecules in the sky act as tiny
- resonators which scatter blue light
- Red sunsets are due to lower frequencies of light that
- survive being scattered in the air
- The greenish blue of water is evidence for the
- absorption of red light
- According to Huygen's Principle, every point on a wave
- behaves as a source of new waves
- Polarization is a property of
- transverse waves
- Light will not pass through a pair of polaroids when their aces are
- perpendicular
- Monochromatic light is light of a single
- wavelength, frequency, and color
- Light from a lit match comes from
- electrons
- Light is emitted when an electron
- makes a transition to a lower energy level
- Compared to the energy put into a laser, the energy of the laser beam is
- less
- In the process of fluorescence, part of the input energy immediately
- becomes internal energy and the rest lower frequency light
- Light from a laser is
- monochromatic, in phase, and coherent
- A watch dial that continues to glow after a week in the dark is almost certainly
- radioactive
- The size of the pupil of your eye depends on
- your mood and the brightness of the room