What is a negative feedback loop?
1 answer:
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Answer:
Hormone levels are changing during menstruation and ovulation. The general trend of hormones after ovulation -when an individual approaches menstruation- is that hormone levels generally decrease.
Explanation:
In a woman's menstrual cycle, hormone levels tend to increase or decrease according to reproductive requirements. On the days close to ovulation, the hormones must prepare for the release of an egg and the preparation of the female reproductive organs for the possibility of an embryo.
If fertilization of the egg does not occur, hormone levels generally tend to decrease until menstruation occurs.
In the attached graph (picture) the behaviour of hormones in an adult woman can be clearly seen, where estradiol, follicle-stimulating hormone, progesterone and luteinizing<u> hormone tend to decrease their levels at the end of the luteal phase, in the proximity of menstruation</u>.
Answer 1:
Diagram is missing in question. Same is attached below.
Position of needle depicts amount of current flowing through the circuit. From the diagram, it can be seen that deflection needle is in between 8 amperes and 9 amperes. This signifies that, current is more than 8 amperes, but less than 9 amperes. Hence correct answer is option B: 8.5 amperes.
Answer 2:
Diagram is missing in question. Same is attached below.
A wavelength is the distance between two successive troughs or two successive crests of the wave. Energy, frequency and wavelength of electromagnetic wavelengths are dependent on each other. In present case, X is a true measurement of the wavelenght. Hence, correct answer is option B: X.
Answer 3:
Diagram is missing in question. Same is attached below.
Magnetic field strength is maximum where the magnetic field density is maximum. From the diagram, it can be seen that, in the region around both north pole and south pole, magnetic field density of identical, as well as very high. Hence, correct answer is option C: Around both poles.
Answer 4:
<span>Alexandra was preparing to go on a hike in the woods. She gathered the equipment she would need and placed it on the counter. By chance, she placed her compass near an electrical outlet. Although the compass was not moving, the compass needle turned because the electrical current in the outlet produced a magnetic field.
Reason: </span> When an electric current flows through a circuit, it generates the magnetic field around it. Due to this, the needle of compass got deflected, since it was in vicinity of magnetic field that was generated upon passage of electric current.
Answer 5:
Diagram is missing in question. Same is attached below.
Correct answer is option B: Using the same number of turns of wire for each electromagnet. This is because, in order to study effect nails in the core of an electromagnet, it would be practical to use same number of batteries and same number of turns of wires in all the experiments. Thus, the variation in magnetism would be solely because of nails present in electromagnet.
Answer 6:
Ms. Markas takes a Thermos bottle filled with hot coffee to work each day. The thermos bottle keeps the coffee hot by slowing heat transfer from the inside to the outside of the container. This is because, thermos acts as in isolated system. An isolated system is one which does not exchange heat as well as matter with surrounding. Due to this, coffee remains hot for long time.
Answer 7:
Correct answer: Option C-Black T-shirt
Reason: The radiation that is absorbed by the compound is dependent on the energy level separation between different electronic energy level. In energy level separation lies in visible region of electromagnetic radiation, then compound is colored. In case of black colour compounds, it absorbs light of all possible wavelenghts.
Answer 8:
Diagram is missing in question. Same is attached below.
Correct answer: option B i.e. have a greater frequency than short wavelengths.
Reason:
We know that, E = hv = hc/∧
where, v = frequency of electromagnetic radiation
∧ = wavelenght.
From above equation, it can be seen that frequency and wavelenght have inverse relation.
Therefore, long wavelengths have a greater frequency than short wavelengths.
Answer 9:
Refractive index is the ratio of the velocity of light in a vacuum to its velocity in a specified medium. In present case, medium used is glass. The best way to determine a glass block's index of refraction is using Snell's Law.
According to Snell's Law, refractive index =
where, Q1 = angle of incident ray
Q2 = angle of refracted ray.
Answer 10:
Joseph studied whether different materials can block certain electromagnetic waves by testing television reception in different parts of the house. At each part of the house, Joseph used a different antenna. The experiment could have been improved by using the same antenna during each trial. Because, currently Joseph has two variable i.e. materials and antenna. This will complicate the experiments, as it would be difficult for Joseph to identify the material that would be best suited for blocking certain electromagnetic waves. On other hand, if Joseph has used same antenna, there would have been only one variable i.e. materials.
Diagram is missing in question. Same is attached below.
Position of needle depicts amount of current flowing through the circuit. From the diagram, it can be seen that deflection needle is in between 8 amperes and 9 amperes. This signifies that, current is more than 8 amperes, but less than 9 amperes. Hence correct answer is option B: 8.5 amperes.
Answer 2:
Diagram is missing in question. Same is attached below.
A wavelength is the distance between two successive troughs or two successive crests of the wave. Energy, frequency and wavelength of electromagnetic wavelengths are dependent on each other. In present case, X is a true measurement of the wavelenght. Hence, correct answer is option B: X.
Answer 3:
Diagram is missing in question. Same is attached below.
Magnetic field strength is maximum where the magnetic field density is maximum. From the diagram, it can be seen that, in the region around both north pole and south pole, magnetic field density of identical, as well as very high. Hence, correct answer is option C: Around both poles.
Answer 4:
<span>Alexandra was preparing to go on a hike in the woods. She gathered the equipment she would need and placed it on the counter. By chance, she placed her compass near an electrical outlet. Although the compass was not moving, the compass needle turned because the electrical current in the outlet produced a magnetic field.
Reason: </span> When an electric current flows through a circuit, it generates the magnetic field around it. Due to this, the needle of compass got deflected, since it was in vicinity of magnetic field that was generated upon passage of electric current.
Answer 5:
Diagram is missing in question. Same is attached below.
Correct answer is option B: Using the same number of turns of wire for each electromagnet. This is because, in order to study effect nails in the core of an electromagnet, it would be practical to use same number of batteries and same number of turns of wires in all the experiments. Thus, the variation in magnetism would be solely because of nails present in electromagnet.
Answer 6:
Ms. Markas takes a Thermos bottle filled with hot coffee to work each day. The thermos bottle keeps the coffee hot by slowing heat transfer from the inside to the outside of the container. This is because, thermos acts as in isolated system. An isolated system is one which does not exchange heat as well as matter with surrounding. Due to this, coffee remains hot for long time.
Answer 7:
Correct answer: Option C-Black T-shirt
Reason: The radiation that is absorbed by the compound is dependent on the energy level separation between different electronic energy level. In energy level separation lies in visible region of electromagnetic radiation, then compound is colored. In case of black colour compounds, it absorbs light of all possible wavelenghts.
Answer 8:
Diagram is missing in question. Same is attached below.
Correct answer: option B i.e. have a greater frequency than short wavelengths.
Reason:
We know that, E = hv = hc/∧
where, v = frequency of electromagnetic radiation
∧ = wavelenght.
From above equation, it can be seen that frequency and wavelenght have inverse relation.
Therefore, long wavelengths have a greater frequency than short wavelengths.
Answer 9:
Refractive index is the ratio of the velocity of light in a vacuum to its velocity in a specified medium. In present case, medium used is glass. The best way to determine a glass block's index of refraction is using Snell's Law.
According to Snell's Law, refractive index =
where, Q1 = angle of incident ray
Q2 = angle of refracted ray.
Answer 10:
Joseph studied whether different materials can block certain electromagnetic waves by testing television reception in different parts of the house. At each part of the house, Joseph used a different antenna. The experiment could have been improved by using the same antenna during each trial. Because, currently Joseph has two variable i.e. materials and antenna. This will complicate the experiments, as it would be difficult for Joseph to identify the material that would be best suited for blocking certain electromagnetic waves. On other hand, if Joseph has used same antenna, there would have been only one variable i.e. materials.